Tsotsil belongs to the Mayan family, within the Cholan-Tseltalan branch, and is the closest sister language to Tseltal, from which it diverged about a thousand years ago. Both derive from a Proto-Cholan-Tseltalan variety of the Chiapas highlands. The language's name, bats'i k'op ('true language'), reflects its speakers' self-designation.

The Tsotsil people inhabit the Chiapas Highlands, in municipalities such as San Juan Chamula, Zinacantán, San Andrés Larráinzar, and Chenalhó. With around half a million speakers, it is, along with Tseltal, one of the most widely spoken Mayan languages in Mexico. Tsotsil culture is notable for its textiles, religious cargo systems, and syncretic traditions such as those of Chamula, which combine Mayan and Catholic rites.

Like Tseltal, Tsotsil came under Dominican evangelization after the conquest of Chiapas, and the friars produced doctrines and vocabularies in the language. Communities were subjected to tribute, forced labor, and resettlement into towns. In 1869-1870 the so-called Chiapas Caste War broke out, an uprising led by Tsotsils of Chamula against oppression and in defense of their religious autonomy.

Tsotsil maintains considerable vitality, with strong intergenerational transmission in numerous Highland communities. It is recognized as a national language of Mexico and has writers, playwrights, and community publishing houses, such as those linked to theater and narrative in bats'i k'op. The 1994 Zapatista uprising, partly rooted in Tsotsil and Tseltal territory, gave new visibility to the language and to Indigenous rights demands.