Even the Spaniards weren’t here in any number. Just a few small isolated settlements like Santa Fe and Los Angeles. The Commanche and Apache ruled north of the Rio Grande and they were a formidable barrier to any Mexican and Spanish presence. It took the US Second Cavalry years to subdue the Apache and Commanche. Mexicans were no match for them.
My post after yours is identical......
All the Spanish rulers in Mexico City had was a territorial claim granted by the Pope. This is all they had....an empty piece of Papal paper that they had no significant military to make good on. To make those territories (Texas etc) truly theirs. We took them in war then made them ours by subduing the native Indians. Jurisdiction was established which the Spanish (in Mexico City) had never been able to