Rio Grande do Sul represents the Riograndense Republic which rebelled from the Empire of Brazil from 1836 to 1845. The independence movement in Rio Grande do Sul state was lead by the Gauchos (Brazillian-German Subculture) somewhat based on Republican principles against the Monarchism of the Brazilian Empire. This long running conflict is known as the War of the Farrapos and historically ended in the eventual defeat of the Separatists and Rio Grande do Sul's reintegration into Brazil.
Rio Grande do Sul has Brazilian primary culture and also accepts Platinean. The state's religion is Catholicism.
It is perfectly possible to survive as Rio Grande do Sul, but you must of course win your initial war with Brazil. In the long run Brazil will become much stronger, so it's best to use your small advantage at the start in order to weaken them (try to take your extra cores from them). After that, you could try to attack Brazil further, or just try to survive as an independent state via strategic alliances with neighbouring countries.
(Note: Rio Grande do Sul should not be confused with the similarly named (and contemporaneous) Mexican rebel nation of Rio Grande, see Republic of the Rio Grande, and neither with Rio Grande do Norte, another Brasillian State).
Tag: RGS - Rio Grande do Sul