The Mexican government was losing population:
"The Texas population was only 3000 in 1810. Texas’ population had actually decreased from 1810 to 1820 due to turmoil caused by the decade-long struggle for independence from Spain (by Mexico).
Desperate to turn the situation around, Mexico's leaders turned to immigration from the United States as a way to bolster Texas’ dwindling population.
The policy would be called colonization. The Mexican government granted contracts to land agents called empresarios. One of the first to plan large scale Anglo colonization of Texas was Moses Austin, a Connecticut businessman.
In 1820, Austin died just as his plans were being approved. His son, Stephen F. Austin, carried on his work and became the first empresario of Texas.
Although the system got off to a good start, the sheer number of Americans wanting to move to Texas quickly overwhelmed the Mexican territory. Within a space of only five years, from 1823 to 1828, the immigrant population had grown from about 500 to more than 30,000"
That was the start of TEXAS.