For three centuries after Columbus's discoveries in the New World, Spanish and Portuguese colonial settlement processes in the Río de la Plata region were periodically disrupted by armed conflict for control of land, resources, seaports, and native labor pools in a vast, dissputed frontier zone in South America. This zone extended across 11°13' oflongitude, the equivalent of approximately 1,290 km (800 mi) at parallel 25°S.

Pope Alexander VI (a Spanish Borgia) issued a Papal Bull in May 1493 that granted Spain title to all lands discovered and to be discovered beyond a line 100 millas west of the Azores and the Cape Verde Islands. (Vander Linden 1916, 1) A year later Portugal's King John negotiated the Treaty of Tordesillas with Spain, which changed the 100 milla papal title limit and set a new line of demarcation in the New World.

In his original Papal Bull the pope named a point in the Azores beyond which he believed 100 millas might easily be measured. He appeared to be unaware that two different island groups which were not on the same meridian were represented. He stated the distance in millas, an old Roman unit of measure not common in either Spain or Portugal. Geographically imprecise, nevertheless, this was the pope's original line of demarcation.

This paper analyzes the origins, sources and the consequences of the differences in interpretation of the Treaty of Tordesillas of 1494, which was negotiated in good faith beetween two powerful maritime nations. The study reveals the territorial conflicts resulting from two errors in treaty language, one of which is an omission in geographic location; the other is incorrect distance measurements. Throughout the colonial era these errors inhibited agreement on defInitive borders between the colonies of Spain and Portugal in the Río de la Plata area.

DEMARCATION LINE RENEGOTIATIONS
King João of Portugal was highly envious of the liberal concessions granted by the Pope to Spain's rulers, which provided them with an absolute monopoly on what he believed would be the lucrative oriental trade in silks and spices. Yet, João dared not challenge the papal authority which had shown his country the same courtesy half-a-century earlier in its African coastal explorations. He knew the Spanish monarchs might be willing to compromise a little in deference to Portugal's superior navy. King João entered into negotiations directly with the Spanish monarchs, Ferdinand and Isabela, in an attempt to gain additional time to search for new lands on his side of this line in the western Atlantic. The negotiations were [end p. 15] shaped by differing points of view held by the respective crowns. The Portuguese had already spent a half-century in explorations to find the sea route to the rich Indies trade and João felt his country was entitled to a fair share of the commerce it would generate. The Spanish rulers, on the other hand, already had papal titles to lands in the Americas, and believed they were being generous with Portugal in the negotiations.

At the treaty negotiations in Tordesillas in 1494 the representatives of both crowns interrpreted the Pope's millas to mean leagues, and agreed to redraw the line at 270 leagues west of the Azores and 370 leagues west of the Cape Verde Islands. It seems incredible that negotiators would make such obvious omissions as setting a definite starting point in each island group, or defining the number of leagues to a degree at the equator; however, those two vital elements were omitted from the negotiated treaty terms (Owens 1977, 422-23).

The westernmost point in the Azores Islands is 27°3'W, whereas the western tip of the Cape Verdes is 5°30'W. From subsequent correspondence and treaty negotiations it is certain that the Spaniards had the center meridian of each island group in mind. King João, however, hoped to acquire as much territory as posssible; and quite predictably, he interpreted the starting point to be at the westernmost point of each island group.

In that emerging age of discovery, every nation had its own system of weights and measures, and its own starting point for the zero meridian. In keeping with this diversity, Spain and Portugal each had several values for the league. In Old Castile, the league was 4.25 km (2.63 mi), or about 22.8 leagues to the degree; the Spanish maritime provinces used 20 leagues to the degree. In Portugal the nautical degree was 17.5 leagues until the negotiations at Tordesillas, when (unbeknown to the naive Spaniards) it was apparently officially revalued to 14.1 leagues to the degree. This, then made each Portuguese league equal to 6.84 km (4.24 mi) (Furlong 1962,646). Since the negotiators neglected to stipulate the distance of a league, and because of the differences in interpretation over the starting point for measurement of distance, it was impossible to determine exactly where the line should be drawn in the New World.

TWO DEMARCATION LINES
The Spanish line fell only 1,569 km (973 mi) west of the center meridian drawn between each specified island group. The geographical coordinate of this line was 47°3'W. In northern South America it fell just east of the mouth of the Amazon River and just east of the present town of Iguape on Brazil's southern coast. The Spaniards felt they had been magnanimous in their concessions at the Treaty of Tordesillas and that they should decide the limits of this gift to Portugal inasmuch as they had made the discoveries and the Pope, had already legitimized clear titles to them.

The Portuguese, on the other hand had everyything to gain and only Spain's good will to lose by objecting; and they knew the Spaniards lacked the naval strength to patrol the entire Atlantic, north and south. They calculated their new western boundary at 50^o 45'W, or 2,532 km (1,570 mi) from the western tips of the two island groups. This placed their line of demarcation 960 km (595 mi) up the Amazon River, putting it near its confluence with the Madeira River in the north; and in the Rio de la Plata opposite present-day Buenos Aires in the south. This also placed the treaty line just west of the site of their future contraband port of Colonia do Sacramento (Figure 1). The Portuuguese later adjusted the treaty line even farther westward to compensate for any movement by the Spaniards in the western Pacific Ocean regions, which Portugal came to consider its own territorial waters.

Controversy over where the original line of demarcation should have been drawn existed from the time the treaty was signed. Since then, scholars have searched the archives for evidence of hidden agendas, diplomatic intrigues, and just plain errors. Davies (1967, 137-44) believes Columbus made a secret pact with King João during a private audience when he landed in Portugal during the return voyage from America in 1493; He further argues, because Columbus had insisted that one degree at the equator equaled only 91.4 km (56.67 mi) while Portugal valued it at 113 km (70 mi), the Portuguese were able to best the Spaniards in the treaty negotiations at Tordesillas. However, the map Davies used to support his conntention locates Brazil's coast line many kilometers east of its actual longitude, and surely less than 270 leagues west of the Azores, had [end p. 16] they been using the 70-mile per degree value, as he contends. Another researcher (Furlong 1962, 646-47) attributes the initial error to gross geographic ignorance on the part of Spain's sovereigns and the Pope, who believed Cape Verde to be within the Azores Island group. Furlong believed that Spain negotiated the Treaty of Tordesillas in good faith, but the advanced knowledge of sea navigation and nautical distances possessed by the Portuguese allowed them to outnegotiate the Spaniards while Columbus, who might have been able to spot the ploy, was away on his second voyage of exploration in the New World.

Renewed Disputes Over Treaty Lines
The dispute over the Tordesilla Treaty line became more technical some years later after Vasco de Gama reached India from the west and Magellan circled the globe from east to west. These voyages of discovery led to new disputes over where to draw the line in the East Indies. Spain had occupied and colonized the Philippines, located more than 1,600 km (1,000 mi) west of where the extended line should have been drawn in the Pacific. Portugal did not want the Philippines, but used that infringement to justify penetration of their South American bandeiras into the Río de la Plata and beyond-all the way to the Andes.

These issues became strong bargaining chips in future negotiations to end European wars. In those disputes Portugal and Spain seemed always to be on opposing sides. The terms of European treaties dealt much grief to Spanish and Portuguese colonial administrators and the Jesuit mission Guaraní Indian pueblos (which occupied much of the disputed Río de la Plata) and altered settlement patterns in important ways during the last decades of the colonial period. Their influence is still evident in the political geography of both Spanish and Portuuguese South America (Owens 1977,424-27).

Spain's la Plata colonies always seemed to fare poorly in these European treaty negotiaations, because Portugal used them as a bargainning chip in a complex geopolitical game. If Portugal needed a strong bargaining point to defend its Far East or European positions, it sent Brazilian bandeirantes into the disputed and sparsely settled Río de la Plata region. Then, if Spain's mission Indian militia drove the Portuguese out, they would demand concessions in other locations for loss of land in the disputed territorial zone. If Portuguese occupation in the Río de la Plata went unopposed, they might later agree to withdraw from the area in exchange for a more highly valued compromise elsewhere. Eventually, it became obvious that the Portuguese really coveted the mines of Potosí in Spain's silver-rich province of Upper Peru. Padre Ruíz de Montoya, who served as spokesman for the Jesuit Province of Paraguay, presented evidence to that effect to the Audiencia de Charcas (Ruíz de Montoya 1639, 47); and President Lizarrau of that Audiencia wrote to the king of Spain in 1637 stating that this was the design of the Portuuguese. Throughout the colonial era the Porrtuguese never ceased in their efforts to attain that objective.

BANDEIRAS-PURPOSEFUL SORTIES

During the 60 year period when the Spanish and Portuguese thrones were merged (1580-1640), the Spanish royal representatives tolerated Brazilian tenitorial penetrations carried out [end p. 17] by the bandeirantes into the disputed frontie rzone. Officials considered them to be no more than troublesome slave-raiding expeditions by unorganized gangs of riff-raff from São Paulo.¹ The very name the Brazilians gave these filibustering expeditions, and their leaders, which means "flag bearers," (bandeiras/ banndeirantes) reveal the Portuguese intent in areas of territorial insecurity in this disputed frontier along the line of demarcation. Even during the period when Portugal was under Spanish rule, the Brazilians never felt allegiance to the Spanish monarchs and did not usually obey Spanish laws; neither did they obey Portuguese laws when it did not suit their purposes.

Some members of the Audiencia de Charcas, the Viceroy's staff and other colonial leaders, began in retrospect to reevaluate these Portuuguese bandeirante explorations for what they surely were-slave raids with coincidental intelligence reconnaissance. This type of activvity provided the Portuguese with the geographhical information they would need for future claims to the disputed territory when it became populated and developed. The Brazilians were intent upon capturing a share of the silver of Potosí. Even Portuguese missionaries were caught up in the expansionist spirit of this nationalistic movement. Some of them accompanied slave hunting bandeiras to southern Spanish Jesuit Indian missions in the Tape (Uruguay) regions in 1636-38; and even the great Brazilian missionary, Padre Antonio Vieira, who became a close adviser to Portuugal's new king, wrote a letter in 1646 to Portugal's ambassador to France recommending a surprise attack and quick offensive against the weakly defended Spanish Río de la Plata colonies. He said it would be easy to capture the mines of Peru which had made Spain so rich. Furthermore, Portugal should move quickly since Vieira had heard that the French were planning to attack the Spaniards in the Río de la Plata region, and Portugal should act first or the French would beat them to it. (Pastells 1912, II 188-89)

The concerns of Vieira were supported by the fact that the French, English and Dutch never recognized the Catholic Pope's authority to apportion the Americas between Spain and Portugal. These nations had already claimed and colonized lands in North America, the Caribbean and the northern coast of South America. Moreover, by the mid-seventeenth century they were openly trading with Spanish colonists in Buenos Aires, a practice expressly prohinited by Spanish royal mercantile trade policies.

PORTUGUESE NATIONALISTIC GOAL---CONQUEST
In Itatín province, north of Asunción, Paraguay, in 1648 and again in 1667 the Brazilians destroyed one Jesuit Guaraní' mission and forced another to move south nearer to Asunción. They captured 4,000 encomienda Indians to be sold as slaves in São Paulo. The latter act forced three Spanish towns supported by the 4,000 Indian laborers to be abandoned for lack of Indian workers needed in the yerba (Paraguayan tea) harvesting industries. This left the entire Itatín province without Spanish settlement (Figure 2). These were not just random slave raids. They were authentic military forays, which were designed to clear out the southern flank of Potosí' so that a secure Portuuguese operation against Peru might be launched from Mato Grosso or Cuyaba if the opportunity presented itself. Other Brazilian attacks were aimed at Asunción's southern flank in 1636-38, 1641-42, 1651, and 1657. All these latter attacks were against the Guaraní Indian misssions; the last four were soundly defeated by the Guaraní' Indian militia (Owens 1977,446).

The Brazilians made minor gold discoveries in Curitiba and along the Atlantic coast near Iguape. The latter find was on Spain's side of the line of demarcation near Santa Catalina Island. However, Spain had never seen fit to fortify Santa Catalina nor otherwise defend this coastline. The Portuguese began supplying these new colonies with tallow, hides, oil and dried beef harvested from Spain's Vaquería del Mar, which consisted of cattle left behind when twelve Tape missions were destroyed in 1636-38 by São Paulo slave hunters who captured nearly 100,000 unarmed Guaraní' mission Indians.

In 1668 Portugal's king established a "new" capitanía (colony) with seat of government in Paranagua. This resulted in contingency plans being drawn up by the Spanish in Buenos Aires, Santa Fé, Corrientes, and Asunción, as well as in the Jesuit Guaraní' Indian missions. The plan was to defend against a possible major Portuguese invasion. Spanish leaders believed the Brazilians planned to occupy Maldonado Island near the Bay of Montevideo on the estuary's eastern shore. The Portuguese [end p. 18] asserted that they intended to occupy this southern coastline to protect it from possible invasion by French or Dutch forces. It was true that many ships from those two nations and also from England and Denmark sailed these waters and engaged in contraband trade at Buenos Aires. Later it became clear that the Portuguese were really after a share of the lucrative illegal commerce passing through the Río de la Plata seaports. In order to lend legitimacy to their territorial claims to this south Atlantic coastline Portugal managed to obtain a Papal Bull issued in 1667 which extended the Bishopric of Río de Janeiro all the way to the shores of the Río de la Plata.

COLONIA DO SACRAMENTO--CONTRABAND PORT
After probing the northern and middle portions of Spain's Río de la Plata frontier for 40 years and finding both to be impractical avenues of approach to their goal of conquest of the Peruvian precious metal regions, the Portuguese in 1680 launched a l4-ship colonization expedition iN the south. In a bold gesture they planted a fort and its town, Colonia do Sacramento, on the east side of the estuary of Río de la Plata opposite Buenos Aires. The preparations took a year. The Spaniards had not expected to find this colony full blown at Buenos Aires' front door, and by the time they learned that this was no ordinary military salient like those in the past, the fort, the town, and the military garrison were completed. The Guaraní Indian missions had been flanked with a permanent military fortress at a strategic location. This garrison could be resupplied from the sea as long as Portugal maintained naval superiority in southern Atlantic waters (Crow 1946, 369-70).

The governor of Buenos Aires mustered his Spanish troops and called up the Guaraní Indian militia, and with this show of force, tried to negotiate with the Portuguese commander to withdraw from this Spanish territory. General Lobo therewith displayed a Portuguese map of South America dated 1678 (Figure 3), that showed Buenos Aires, Asunción, Tucumán and Pootosí all to be located on Portugal's side of the line of demarcation. He then presented orders from his king that read:

" ... populate the southern lands which are within the Portuguese Demarcation, and continue to the Río de la Plata and Buenos Aires, where the Spaniards have established several colonies in lands belonging to this Crown."

The Buenos Aires governor ordered his forces to take the fort. The Guaraní militia, which numbered 3,000, immediately scaled the walls and in three hours captured the fort with heavy losses to the 700 man Portuguese garrrison. Peace negotiations in Spain restored the fort to Portugal in 1681, establishing a century-long routine whereby the Guaraní missions and Colonia were to serve as chess pieces in European Wars, with the monarchs calling the moves for Río de la Plata by mail. Royal orders would come for the Guaraní to take Colonia, followed by peace talks which almost always ordered it returned to the Portuguese/Brazilians. During the first 70 years of this capture and restore gambit, no firm attempt was ever made to fix definite boundaries between the colonies of the two nations. Between each conflict and its peace negotiations, Brazilians occupied more of the disputed territory, invoking the principles of Uti Possedites Juris. In the century following Portuguese founding of Colonia, the Guaraní militia were mobilized to expel or lay siege to it no fewer than ten times:[end p. 19] 1680 (twice), 1700, 1702, 1704, 1718, 1721, 1724, 1736, and 1762

Changed Political Purpose for Colonia

The Portuguese were defeated in every encounter with the Guaraní militia in the interior provinces in the first years of their renewed independence from Spain (1640). This prompted the founding of Colonia, where they hoped to have better luck against Spanish troops. Their initial encounter with the Guaraní in this location spilled enough Portuguese blood to connvince them that military force here would be just as unproductive. They decided to postpone for the present the plan to annex by force of arms the Peruvian silver mines. However, the recovery of Colonia's port in 1681 permitted a second option, that of its use as a base for their cattle and hide export business, for slave smuggling into Spain's colonies; and as a safe port for ships of other maritime nations engaging in these illegal smuggling operations.

The Portuguese also used Colonia to avail themselves indirectly of at least a part of the wealth of Potosí. During the 21-year period (1681-1702) that the Portuguese operated Colonia as a contraband port the proportion of illegal Peruvian silver passing through the site multiplied many times. Thus, Portugal's goal of gaining access to the Peruvian silver region was effectively accomplished, and with considerably less cost in human lives and treasures than would have been the case by force of arms. Portugal had found a profitable [end p. 20] way to mine Spain's Peruvian silver without pick and shovel (Owens 1977,453-54).

The volume of trade through Colonia's port, swollen by the hundreds of ships of all nations which used it, had become so valuable to Portugal's economy that continuance for its commmercial value alone became an end in itself. At the start of the War of the Spanish Succession in 1702 Guaraní militiamen were again called out to lay siege to the port. The Guaraní succceeded in forcing the Portuguese out, but they regained Colonia again in 1713 as a result of the Treaty of Utrecht In addition to the contraband trade, the Portuguese exploited cattle from the vaquería del mar to supply Brazil's own mining and sugar industry needs with hides, tallow and dried beef, and also satisfied the demands of ships from other sugar producing nations that were engaging in Colonia's contraband trade. Inevitably, within only a few years after the Portuguese return to the port their wanton slaughter of cattle had nearly depleted the almost inexhaustible vaqueria del mar.

Thus, the Portuguese came in conflict with the Guaraní mission Indians which depended on the Vaquería for mission meat supplies. Alarmed, the Indians reported this rapid depletion to the governor of Buenos Aires, who ordered them to drive the remaining herds north, out of the reach of the Portuguese at Colonia. The Portuguese responded by arming the nomadic Charrúa Indians, who were always hostile to the Guaraní, and leading them on rustling raids into enemy territory. This tactic failed to produce enough cattle to supply Brazil's southern colonies, let alone any surplus to sell to her allies. Seeing the flow of Peruvian silver dwindle, and finding itself in an extremely favorable negotiating position at the end of the War of the Austrian Succession in 1749, Portugal took advantage of the chance to exchange this thorn in Spain's side for a portion of the Guaraní missions--a thorn in Portugal's side for 80 years. At the same time Portugal attempted to establish firm accords on the much-disputed boundary region of Río de la Plata.

TREATY OF LIMITS (1750)
In the 1740s, Spain and England fought the War of Jenkins' Ear, which merged into the War of the Austrian Succession. In the latter war King Philip V of Spain attempted to capture kingdoms in Italy for his sons by his second wife, who was an Italian Princess. He died before the war's end, and Ferdinand VI, his son by his first wife, took power in time to negotiate the peace. Portugal's good fortune in these negotiations derived from the fact that Ferdinand's wife, who had more influence over him than anyone else, was Barbara Braganza, sister of the King of Portugal. Separate treaties were negotiated with each belligerent, one each in 1748 (Aux-la-Chapelle), 1749 (Aquisgran), and 1750 (Treaty of Limits). In the first two treaties, Spain acquired the two Italian kingdoms for Ferdinand's half brothers, one of whom in 1759 became King Charles III of Spain. Spain paid for the two kingdoms in Italy with concessions given to Portugal in the third pact, known as the Treaty of Limits. This treaty pertained primarily to the American colonies of the two countries in Río de la Plata. This treaty was negotiated in such secrecy that not one colonial official was consulted, and even the king's Jesuit confessor was ignorant of its terms until after the treaty was signed (Bertrand and Petrie 1945,264-92).

The Treaty of Limits ceded Colonia do Sacramento to Spain, in return for which Spain agreed to a new southwestern boundary with Portugal in the Río de la Plata. This new limit approximated the present Brazilian boundaries with Argentina and Uruguay. The vast territory ceded to Portugal included over 400,000 km² (150,000 mi²) of land which that country had never occupied nor to which it had any other legitimate claims. Contained within this area were seven of the Guaraní Indian mission pueblos that were located east of the Río Uruguay, with all their ranch lands, plantations of cotton and cultivated yerba. The area also contained several yerba plantations and ranches belonging to missions with pueblos situated west of the Río Uruguay. The treaty terms permitted the Guaraní to remain in place under Brazilian Portuguese control or to move west of the Río Uruguay or south of the Río Ibicuí. Portugal would pay an indemnity of 4,000 pesos per mission. Inasmuch as there were 29,191 Indians in the seven missions, this amounted to less than one peso per inhabitant. Missions west of the Río Uruguay which lost ranches and plantations were not indemnified for their forfeitures. Estimates of the value of buildings, improved lands and orchards vary but one mission priest placed it in excess of 16 million pesos. The Jesuit mission priests and their colonial superiors protested this gross[end p. 21] injustice, all except the Padre General in Rome, who ordered the Jesuits to seek new lands for their Indians (Figure 4).

THE GUARANI WAR
The Guaraní, who fought the Brazilians for 130 years to avoid enslavement, did not, under any circumstances, want to be delivered into the hands of their mortal enemies. They tried to move south of the Río Ibicuí but were met by the hostile Charrúa, armed by the Portuguese as noted above. Other Guaraní were thwarted in their attempt to move west of the Río Uruguay by Portuguese-sponsored trouuble-makers there. The Guaraní Indians of the seven missions refused to move and fought a bitter four-year guerrilla war against the commbined armies of Spain and Portugal (Furlong 1962, 657). Defeated, with much of their lands and homes destroyed and half their population dead or fugitive, they were deported west of the Río Uruguay in 1756 without personal belongings, and with only the clothes on their backs, to live as refugees among other missions. The Brazilians then occupied and plundered the former Guaraní lands until 1759.

King Charles III, an ally of France, ascended the Spanish throne in 1759 during the Seven-Year's War. Under the terms of the Treaty of Paris, which ended that war, the 400,000 square kilometer Guaraní mission territory was returned to Spain, which once again gave up its claim to the port of Colonia do Sacramento.

VICEROYALTY OF LA PLATA
In 1776 Charles III raised Río de la Plata to the status of a Viceroyalty in an attempt once and for all to halt the westward expansion of Portu [end p.22] gal and to reestablish Spain's control of contraband commerce in the region. The new viceroy, Cevallos, leading a force of 116 vessels and 10,000 men, recaptured Colonia, invaded Brazil's southernmost province and was set to annex Río Grande do SuI when he was recalled in 1777 as peace was again declared in Europe. This time Spain had the advantage due to its occupation of the Brazilian territories, and dicctated the terms of the settlement in its own favor. Spain was able to keep Colonia, all of Uruguay and the mission territories. In return, Portugal received vast regions west of the Spanish line of demarcation in the interior part of the continent. Only a very few hectares of these ceded lands had the Brazilians ever occupied, and none had they fortified until just beefore the boundary marker commission arrived to mark the borders. The present boundaries of Brazil with Peru, Bolivia, Ecuador, Colombia and Venezuela are approximately the same as ceded to Portugal in these and earlier treaties with Spain's monarchs (Crow 1946, 371).

CONCLUSION
Territorial conflicts in the Spanish and Portuuguese Río de la Plata colonies occurred mainly in a broad, disputed frontier zone created by the differing interpretation of the Treaty of Tordesillas that were held by the two nations. The Brazilian bandeirantes from São Paulo moved freely through this disputed zone while the two crowns were merged (1580 to 1640) and, in the process, destroyed 26 Guaraní Indian missions licensed by the Spanish crown. They captured over 100,000 unarmed Indians and sold them in the São Paulo slave markets. These bandeiras were armed military reconnaissance missions searching for a way to annex the Potosí silver mines of Upper Peru to the Portuguese colony.

After 1647, when the Guaraní Indian militia became the official military garrison opposed to Brazil, the Río de la Plata governors called them to active duty many times to fight Portuguese territorial intrusions. Often the victories gained in battle in the Río de la Plata by the Indian militia were bargained away in peace negotiations which ended European wars. Similarly, Brazilian gains made by their bandeirantes in the hinterlands were just as likely to be traded for something more highly prized by Portugal in the Pacific region, Africa or Europe.

The Portuguese, in 1680, founded the port and fort of Colonia do Sacramento on the east shore of the La Plata estuary opposite the Spanish port of Buenos Aires in order to take advantage of the lucrative illegal contraband trade with Buenos Aires merchants and to harvest the vast wild cattle herds in the Vaquería del Mar. In doing so they also discovered a bloodless way to tap into the rich silver lode of Potosí, and to establish their claim to lands in the dissputed frontier zone by right of their occupation and economic exploitation.

The persistence of the Brazilian bandeirantes and the Guaraní Indian militia in their respective endeavors exerted great influence upon the shaping of the social, economic and political landscapes of the Río de la Plata region. It took almost three centuries of conflict in the disputed frontier zone before Spain and Portugal came to an agreement on where the boundaries of their respective colonies should be in the Río de la Plata region. However, the work of establishing territorial ownership had really been determined in the disputed boundary zone by missionaries, colonial settlers, bandeirantes and mission Indian militia.

NOTE
1. Many of these so-called riff-raff leaders and their irregular troops were later commissioned as regulars. They fought to expel the Dutch who had invaded Pernambuuco, and then to suppress the Negro rebellions following Brazil's successful action against the Dutch.

REFERENCES CITED
Bertoni, M. S. 1922. La Civilización Guaraní, Parte I, Prehistoria-y-Protohistoria. Puerto Bertoni, Alto Parana, Paraguay: Moires Santiago Bertoni.

Bertrand, L. and C. Petrie. 1945. History of Spain. 2nd ed. London: Eyre & Spottiswoode. Brabo, F. J. 1872. Colección de obras y documentos relativos a la expulsión de los Jesuitas de la República Argentina y del Paraguay en el reinado de Carlos III . Madrid: Establecimiento Tipografía de Jose Marfa Perez. (Microfilm copies of the original documents in the Archives of the Indies are included in the Pastells Collection listed below.

Crow, J. A. 1946. The Epic of Latin America. Garden City, NY: Doubleday & Company Inc.

Davies. A. 1967. Columbus divides the world. Geographical Journal 133(9): 337-44.

Furlong, G., S. J. 1962. Misiones y sus Pueblos de Guaraníes. Buenos Aires: Imprenta Balmes.

Hernández, P., S. J. 1913. Organización social de las doctrinas guaranías de la Companía de Jesus. Vol. I. Gustavo Gili, ed. Barcelona: Gustavo Gili. [end p. 23]

Keen, B., ed. 1960. The Life of the Admiral Christoopher Columbus, by Ferdinand Columbus (transl. and annotated). The Folio Society.

Morrison, S. E. 1942. Admiral of the Ocean Sea. 2 vols. Boston: Harvard University Press.

Núñez Cabeza de Vaca, A. 1891. Commentaries of Alvar Núñez Cabeza de Vaca (from the original Spanish edition). In Conquest of the River Plate 1535-1555, transl. Luis L. Domínguez, 95-262. London: Printed for the Hakluyt Society.

Owens, D. J. 1977. A Historical Geography of the Indian Missions of the Jesuit Province of Paraguay; 1609-1768. Ph.D. dissertation, University of Kansas.

Pastells, P., S. J. 1912. Historia de la Compañía de Jesus en la Provincia del Paraguay, segun los docuumentos originales del Archivo General de Indias. 8 vols. 9 tomos. Madrid: Vols. 1-5 pub. by author,; Vols. 6-8, Libreria General de Victoriano SlWeZ.

Ruíz de Montoya, A., S. J. 1639. Conquista espiritual hecha por Los religiosos de la Compañía de Jesús en Las provincias de Paraguay, Paraná, Uruguay, y Tape. Madrid: Imprenta del Reyno.

Vander-Linden, H. 1916. Alexander VI and the demarcation of maritime and colonial domains of Spain and Portugal, 1493-1494. American Historical Review 22(1):1-9.

Resumen
Rivalidades territoriales entre España y Portugal en la región del Río de la Plata existieron durante todos los tres siglos de la colonia. Estos connflictos se debieron a las interpretaciones distintas de las dos naciones que firmaron el Tratado de Tordesillas. Estas diferencias crearon una zona fronteriza disputada que extendió por 110 de longitud entre las colonias Sud Americanas de España y Portugal. Las ricas minas españolas de Potosí quedaron muchas leguas hacia el oeste de esta zona, sin embargo, los portugueses hicieron esfuerzos constantes para anexarlas a sus colonias brasileñas. Las negociaciones de paz que terminaron las guerras europeas de la temporada casi siempre incluyeron condiciones que cambiaron los límites de la zona de disputa, con consequencias económicas, sociales, políticas y geográficas. Dos instituciones únicas características de Ia región influyeron tremendamente en la evolución política-geográica de La Plata: (1) la guardia Guaraní de las misiones jesuitas y (2) los banndeirantes brasileños.
Palabras clave: bula del Papa, viaje de descubrimiento, yerba mate, vaquería del mar, bandeirantes, bandeira, guardia Guaraní, Uti-Possedites Juris, Colonia do Sacramento. [end p. 24]