On galvenston island, the native americans sustained the europeans with

The rulers of native American, European, African, and Asian empires and kingdoms secured and sustained their power by: (1) they made sure (or at least tried) that only one family must rule, (2) they made sure that their military is strong, (3) They see to it that connections must be made with neighboring powers and if they do not cooperate, they must be destroyed, and (4) they made sure that their subordinates see them as gods.
The ordinary people benefited from these methods of power preservation because all they needed to worry about was food. The disadvantage however is since the seat of power is only given to the ruling elite, they got no say in politics. Plus if the rulers decide their empire or kingdom will go to war, they basically end up being the victims of it.