Mad King James said:The reason why Europeans didn't just do the same thing Spain did in Central America isn't from lack of resources or will. England was just as greedy as Spain was. The reason why is because they couldn't.
In Central and South America, the Spanish COULD conquer full prosperous cities with functioning economies, convert them to catholicism, and milk them without any significant investment in infrastructure. This cannot be said of the Iroquois, who despite having a functional confederacy-based state, simply did not have the infrastructure of a civilization. They COULD have eventually developed one, they by no means lacked any of the neccisary ingredients for one, but they just didn't at the time, nor did one come to exist after European colonization. What did happen was the Iroquois were either assimilated into European colonies or driven off their land. This is exactly what natives do in EU2. As they were a very formidable force, I would personally advise that Iroquois, Cherokee and Hurons have an absolute HORDE of native strength and aggression, that it would take a determined army to defeat them.
That would put them in the hands of the human player only, and the AI would expend valuable resources for no gain.