The colonization of Texas by Mexico started in 1821, when Mexico won independence from Spain, and made Texas part of the new nation. The northern and eastern regions remained in the hands of the Indian tribes because some were hostile to Mexican rule. Attempts to interest large numbers of Mexicans to settle in Texas failed. To create a buffer between the more populous regions of Mexico and the Indians to the north and the aggressively expanding United States on the east, the Mexican government issued colonization contracts to permit home seekers to enter Texas under specific provisions. Initially, thousands of settlers flooded into Texas; however, an unstable political situation in Mexico City coupled with stricter control of law enforcement caused many Texans to become disgruntled. History illustrates these events to be the groundwork for the beginning of the Texas Republic.