Answer: Fertile Soil
Explanation:
Before the Spanish came to Texas, the Eastern part of Texas was occupied by Indians who took advantage of the fertile land to practice extensive agriculture.
With the arrival of the Spanish however, their numbers decreased and they increasingly turned to raiding farms granted to Mexican settlers by the Government.
When Mexico got independence from Spain they became more worried about the Indian raids and sought to increase the non-indian population so they invited Americans to settle there and offered them land to do so.
The result was that Americans seeing the fertile lands that could be useful for cotton came in their numbers and eclipsed even the Mexicans in number.
Texas would eventually come under American control.
