Intellectual disability is a condition diagnosed in individuals with deficits in intellectual functioning beginning in childhood and

The answer is childhood and poor adaptive behaviors. 
Intellectual disability is a state which individual is incapable to adapt things surrounded him or her. Everyone who was eligible for a diagnosis of mental slow development and progress is entitled and qualified for a diagnosis of intellectual disability. Individuals having intellectual disability shows random sheer incompetence, poor understanding, poor adaptation in behaviors of real-life skills such as cleaning, grooming, or avoiding danger, the ability to work, take personal responsibility, and social skills.

They wanted to make slaves out of them.they wanted force them to move off their landthey wanted to make them grow crops for very little pay.they refused to speak native american languages