The Zapotecan languages are a group of related Oto-Manguean languages which descend from the common Proto-Zapotecan language spoken by the Zapotec people during the era of the dominance of Monte Albán.
The Zapotecan languages are usually divided into two branches; the Zapotec languages and the Chatino languages. Minor variants, including Solteco Zapotec and Papabuco, are considered by some authors to be divergent Zapotec languages. Based on analysis of the pronominal systems and other innovations, the following relationship has been proposed:
Glottochronological estimates place the time of diversification of Proto-Zapotecan to 24 centuries ago; that is to say, about a millennium more than the time of diversification for Zapotec itself.
Since the 19th century, a relationship between the Zapotecan languages and the Mixtecan languages within Oto-Manguean has been recognized; these two sub-families would form an Eastern branch of Oto-Manguean.
The following table shows the pronominal subjects en Proto-Zapotec, Chatino, Papabuco, and Proto-Zapotecan:
The numerals have the following tentative reconstruction: