Beginning 700 AD, locate the right people, the right place, the right resources, the right leader (reasonable likeness), and the right ideas to build up a Native American tribe or nation based north of present-day Panama to survive the European invasion in very good shape and beat the invaders back to an extent that the NA people becomes widely recognized by 1800, at the latest, as the sole legitimate rulers of their territory. I'd like to think even fanboys of the ERE and the Gepidae could have fun with this!