The indigenous nomads of the area around the river La Plata resisted Spanish intrusion, which began with the first fouding of Buenos Aires by Pedro de Mendoza in 1536. Argentina was part of Spain Viceroyalty of Peru until reforms in the Bourbon dynasty and a need to defend against Portuguese encroachment from Brazil led to the formation of the Viceroyalty of La Plata, including Argentina, Bolivia, Paraguay and Uruguay, in 1776. Following the relaxation of trade restrictions two years later, Buenos Aires grew from a small town to a city of 50,000 by 1800. A provisional junta of the Provinces of Río de la Plata was established in 1810 after the Napoleonic occupation of Spain, and in 1816 the United Provinces of the Río de la Plata declared their independence.

After independence the question of political relations among the United Provinces was settled by a federalist solution in which the provinces disolved into a number of practically independent republics. In 1824, a constituent assembly created the office of president, first held by Bernardino Rivadavia. However, the failure to ratify a workable constitution caused Rivadavia to resign.

Juan Manuel de Rosas became governor of Buenos Aires in 1829 and president over the construction of a federal agreement between the provinces in 1831. Rosas governed Buenos Aires with an iron hand until his expulsion in 1852. The other provinces formed the Argentine Federation, but Buenos Aires refused to join. Buenos Aires and the Argentine Federation entered into war between 1859 and 1861; they reached an agreement on the inclusion of Buenos Aires in the Argentine Republic in 1862.

Argentina joined Brazil and Uruguay in a war (1870) against Paraguay. During the latter part of the 1870's, the government took the initiative against the indigenous populations of Patagonia and Tierra del Fuego, which were partitioned with Chile. Immigration from Europe, especially from Spain and Italy, resulted in enourmous growth from the mid-19th century. In 1869, there were 2 million inhabitants; by 1914, 8 million; by 1955, 19 million; and by 1990, 32 million. Prior to World War II, Argentina was acutely Eurocentric, with an eye to British finance and French culture; this has changed since.*

* from The New York Times Almanac 2000 - Penguin Reference.