The decision of the U.S. Supreme Court that held that private citizens could not purchase lands from Native Americans. ... Thus, all that the opinion holds with respect to aboriginal title is that it is inalienable, a principle that remains well-established law in nearly all common law jurisdictions.
Around 110,200 to 200,000
The main reason why Spain established colonies in Texas and California was because they saw a great advantage to having territory in the Americas, and these missions united many local people.
The goal of the encomienda system was to make the Native American slaves for the purpose of using these slaves as a labor source.
However, this system did not succeed as the Native American were experts with the land and could easily escape. However, not being immune to diseases, they eventually died as a result of sickness.