The… mexican government? The national archive? Dunno, ur pick really. Soon after independence even the first laws of colonization, and they are explicitly called that, were redacted. (El Congreso General Constituyente decretó la primera ley de colonización el 18 de agosto de 1824.)
Most of the Septentrión was settled during the republican era and if you’re playing AoE3 then guess what, you’re explicitly founding a colony as soon as the game starts.