Fasctinating stuff. I saw a great documentary on Ponce de Leon a while back, and his biographer described the Seminoles as violent or vicious - "savages" as it were. But, as the documentary pointed out, Ponce de Leon was probably not the FIRST to wander to Florida, thinking it was another island, as the nearby islands were already well established by then. It's suspected that the Seminoles already had plenty of contact with Spanish slave traders and were already not happy with them once Ponce came along.
So it's pre-1510 even. We just don't know the date.
The Seminole Tribe settled in Florida in the 1700s. The tribe was formed from several smaller tribes in Georgia and Florida. Some of these tribes were the Oconees, Hitchitis, Creeks, and Miccosukees. They joined together to make one larger tribe. During the 1800s, they were joined by Native Americans from other tribes and also from African-Americans who were able to escape from slavery.