From the site:
Pre-Columbian civilization in the fertile, wooded region that is now Paraguay consisted of numerous seminomadic, Guarani-speaking tribes, who were recognized for their fierce warrior traditions. They practiced a mythical polytheistic religion, which later blended with Christianity. Spanish explorer Juan de Salazar founded Asuncion on the Feast Day of the Assumption, August 15, 1537. The city eventually became the center of a Spanish colonial province. Paraguay declared its independence by overthrowing the local Spanish authorities in May 1811.
The country's formative years saw three strong leaders who established the tradition of personal rule that lasted until 1989: Jose Gaspar Rodriguez de Francia, Carlos Antonio Lopez, and his son, Francisco Solano Lopez. The younger Lopez waged a war against Argentina, Uruguay, and Brazil (War of the Triple Alliance, 1864-70) in which Paraguay lost half its population; afterwards, Brazilian troops occupied the country until 1874. A succession of presidents governed Paraguay under the banner of the Colorado Party from 1880 until 1904, when the Liberal party seized control, ruling with only a brief interruption until 1940.
In the 1930s and 1940s, Paraguayan politics were defined by the Chaco war against Bolivia, a civil war, dictatorships, and periods of extreme political instability. Gen. Alfredo Stroessner took power in May 1954. Elected to complete the unexpired term of his predecessor, he was re-elected president seven times, ruling almost continuously under the state-of-siege provision of the constitution with support from the military and the Colorado Party. During Stroessner's 34-year reign, political freedoms were severely limited, and opponents of the regime were systematically harassed and persecuted in the name of national security and anticommunism. Though a 1967 constitution gave dubious legitimacy to Stroessner's control, Paraguay became progressively isolated from the world community.