From Elk v Wilkins
Indians born within the territorial limits of the United States,members of and owing immediate allegiance to one of the Indian tribes (an alien though dependent power), although in a geographical sense born in the United States, are no more "born in the United States and subject to the jurisdiction thereof," within the meaning of the first section of the Fourteenth Amendment, than the children of subjects of any foreign government born within the domain of that government, or the children born within the United States of ambassadors or other public ministers of foreign nations.
This view is confirmed by the second section of the Fourteenth Amendment, which provides that "Representatives shall be apportioned among the several states according to their respective numbers, counting the whole number of persons in each state, excluding Indians not taxed."
The fourteenth amendment makes them a separate group from foreigners since foreigners would be taxes on property they own. Elk also makes it clear that the only foreigners not subject to the jurisdiction are foreigners born in other countries and children of ambassadors within the US.