Mexican Texas is the historiographical name used to refer to the era of Texan history between 1821 and 1836, when it was part of Mexico. Mexico gained independence in 1821 after winning its war against Spain, which began in 1810. Initially, Mexican Texas operated similarly to Spanish Texas. Ratification of the 1824 Constitution of Mexico created a federal structure, and the province of Tejas was joined with the province of Coahuila to form the state of Coahuila y Tejas. In 1821, approximately 3,500 settlers lived in the whole of Tejas, concentrated mostly in San Antonio and La Bahia, although authorities had tried to encourage development along the frontier. The settler population was overwhelmingly outnumbered by indigenous people in the province. To increase the number of settlers, Mexico enacted the General Colonization Law in 1824, which enabled all heads of household, regardless of race, religion or immigrant status, to acquire land in Mexico. The first empresarial grant had been made under Spanish control to Stephen F. Austin, whose settlers, known as the Old Three Hundred, settled along the Brazos River in 1822. The grant was later ratified by the Mexican government. Twenty-three other empresarios brought settlers to the state, the majority coming from the American South, while only one colony was settled by Mexican nationals, and two by European immigrants. Mexico officials became concerned about attitudes among the Anglo-Americans in Tejas, for instance, their insistence on bringing slaves into the territory. The legislature passed the Law of April 6, 1830, which prohibited further immigration by U.S. citizens. The government established several new presidios in the region to monitor immigration and customs practices. Angry colonists held a convention in 1832 to demand that U.S. citizens be allowed to immigrate to Tejas. At a convention the following year, colonists proposed that Texas become a separate Mexican state. Although Mexico implemented several measures to appease the colonists, Antonio Lopez de Santa Anna's measures to transform Mexico from a federalist to a centralist state appeared to be the catalyst for the Anglo-Texan colonists to revolt. The first violent incident occurred on June 26, 1832, at the Battle of Velasco. On March 2, 1836, Texians declared their independence from Mexico. The Texas Revolution ended on April 21, 1836, when Santa Anna was taken prisoner by Texians following the Battle of San Jacinto. Although Texas declared its independence as the Republic of Texas, Mexico refused to recognize