Whose Land is it, Really?

Primary tabs

I know I’m treading on dangerous ground today, but nagging questions have been buzzing in my head and I need your help in answering them.
As I understand it, the Spanish stole Texas and California from the ancestors of the indigenous people who are now trying to swarm across America’s southern border. And America acquired Texas and California after those territories kicked out the Spanish.
If this is true, does America have a moral obligation to give special consideration to the indigenous people who occupied the seized territories?