Yes, I remember the role of the Jesuitic Guaranies in the retaking of Sacramento.
It otherwise can't be that hard, several tribes were later more than eager to ally with men than Rosas and Mitre provided the pay was good enough, although I don't know if the first Argentine Government have enough money to bribe the southern tribes, and that I don't know which tribes are those, since the tribes that Rosas had in his pocket resided in southern Chile in the 1810s..
A very cool scenario would be to have Pampa Indians fighting the British in 1806/7. For those who don't know, Pampa Indians of that time where nomad horse riders, similar to contemporary Amerindians from Norhtamerican Plains (but, IIRC, they used more spears and
boleadoras than bows and arrows, and were more in touch with non Indians through trade and other means of communication than NorthAmerican Indians).
Apparently, a certain leader (I think it was a Spaniard, a criollo or a mestizo from Chile who had some influence among these tribes) presented himself to the authorities in Santa Fe 1806 the and offered the help of thousands of Indian horsemen to expell the "Colorados" (
litterarly "the Reds"; it was the word he used to refer to the British soldiers) from Buenos Aires. He's offer was declined.
Guaranies like Andres Guacurari also had important role in places like the Misiones, although mostly fighting Brazilians and during Artigas' civil war in the north. .
I didn't know this
I dunno about Bolivia and Peru, although they do have a history of rising against against the Spaniards, if Tupac Amaru II is of any indication.
Nor do I, but who can they fight. After all, Spanish control over Perú and Bolivia wasn't threateneed by any foreign power...
Maybe Mexico is a better place. Might tibes living in Northen Mexico have been allies of either Mexico or the US during the Texas Secession and/or the Mexican-American war???
EDIT: I just realised the original post (which I myself wrote) says South America. But it doesn't matter.