After Mexico gained independence from Spain in 1821, the Mexican government began to implement laws to abolish slavery throughout the country. In 1829, President Vicente Guerrero issued a decree that abolished slavery in Mexico, including in the state of Coahuila y Tejas, which included what is now Texas.
However, the enforcement of this law was not immediate or consistent. Many slave owners in Texas continued to hold slaves, and the Mexican government did not have the resources or the political will to fully enforce the ban on slavery.
In 1830, the Mexican government passed the Law of April 6, which placed further restrictions on immigration to Texas from the United States, in part because many American settlers in Texas were slave owners. The law also reaffirmed the ban on slavery in Texas.
Despite these laws, slavery continued to be practiced in Texas, particularly by Anglo-American settlers who were not necessarily loyal to the Mexican government. The issue of slavery became one of the main sources of tension between Texas and Mexico, ultimately leading to the Texas Revolution in 1835 and the establishment of the Republic of Texas as an independent country in 1836.
In summary, slavery was officially banned in Texas after 1830, but enforcement was weak, and many Texans continued to hold slaves.