Soon after, the encomienda system was introduced, which reduced most of the indigenous population to serfdom and many even as slaves as a form of tribute and way of locking in a labor supply for tax payments. The conquistadors brought previously unknown diseases. This, as well as overwork on plantations, dramatically decreased the indigenous population. The Spanish also established missions, mostly under the Dominicans, with the Diocese of Chiapas established in 1538 by Pope Paul III. The Dominican evangelizers became early advocates of the indigenous' people's plight, with Bartolomé de las Casas winning a battle with the passing of a law in 1542 for their protection. This order also worked to make sure that communities would keep their indigenous name with a saint's prefix leading to names such as San Juan Chamula and San Lorenzo Zinacantán. He also advocated adapting the teaching of Christianity to indigenous language and culture. The encomienda system that had perpetrated much of the abuse of the indigenous peoples declined by the end of the 16th century, and was replaced by haciendas. However, the use and misuse of Indian labor remained a large part of Chiapas politics into modern times. Maltreatment and tribute payments created an undercurrent of resentment in the indigenous population that passed on from generation to generation. One uprising against high tribute payments occurred in the Tzeltal communities in the Los Alto region in 1712. Soon, the Tzoltzils and Ch'ols joined the Tzeltales in rebellion, but within a year the government was able to extinguish the rebellion.