The territory of modern Argentina was part of the Spanish Viceroyalty of the Río de la Plata, with its capital city in Buenos Aires, seat of government of the Spanish viceroy. Modern Uruguay, Paraguay and Bolivia were also part of the viceroyalty, and began their push for autonomy during the conflict, becoming independent states afterwards. The vast area of the territory and slow communications led most populated areas to become isolated from each other. The wealthiest regions of the viceroyalty were in Upper Peru (modern-day Bolivia). Salta and Córdoba had closer ties with Upper Peru than with Buenos Aires. Similarly, Mendoza in the west had closer ties with the Captaincy General of Chile, although the Andes mountain range was a natural barrier. Buenos Aires and Montevideo, who had a local rivalry, located in the La Plata Basin, had naval communications allowing them to be more in contact with European ideas and economic advances than the inland populations. Paraguay was isolated from all other regions.