What was Mexico's position on slavery?

The abolished it in 1829 ...

Explanation:

In 1829 Mexico decided to abolish slavery, but they made an exception for Texas.

By the 1800s, most slaves in Texas had been brought by slaveholders from the United States. A small number of slaves were imported illegally from the West Indies or Africa. In the 1830s, the British consul estimated that approximately 500 slaves had been illegally imported into Texas. By 1836, there were approximately 5,000 slaves in Texas.