Thank you for the clarification. Have you read the work of Paul Kirchhoff? I haven’t but I known that he was the German anthropologist who coined the term Mesoamerica in the 1940’s. So I hope you can follow in his footsteps in making your proposed term Tortuamerica accepted by academia someday. Other terms used in Mexican academia are Aridoamerica and Oasisamerica but those names I believe aren’t used much outside of Mexico. In fact Oasisamerica is the American Southwest and I think the term used for its people is the Puebloans (not sure if it is an umbrella term).
As for this thread I would really like to see a civ based on the Guaraní of the Jesuit reductions in Paraguay as depicted in the movie The Mission and described in this thread:
But being more realistic I think adding a whole new civ is a lot of work and probably the most feasible option is to rework current civs and revolutions or even add new revolutions. So I´m OK with anything the devs do to make the game more fun. I sincerely hope you can still enjoy this game even if we don´t get what we want (Lakota rework for you and Guaraní-Jesuits and Habsburg Austrians for me) 