The Oto-Manguean or Otomanguean languages are a large family comprising several subfamilies of indigenous languages of the Americas. All of the Oto-Manguean languages that are now spoken are indigenous to Mexico, but the Manguean branch of the family, which is now extinct, was spoken as far south as Nicaragua and Costa Rica. Oto-Manguean is widely viewed as a proven language family. However, this status has been recently challenged. The highest number of speakers of Oto-Manguean languages today are found in the state of Oaxaca where the two largest branches, the Zapotecan and Mixtecan languages, are spoken by almost 1.5 million people combined. In central Mexico, particularly in the states of Mexico, Hidalgo and Querétaro, the languages of the Oto-Pamean branch are spoken: the Otomi and the closely related Mazahua have over 500,000 speakers combined. Some Oto-Manguean languages are moribund or highly endangered; for example, Ixcatec and Matlatzinca each has fewer than 250 speakers, most of whom are elderly. Other languages particularly of the Manguean branch which was spoken outside of Mexico have become extinct; these include the Chiapanec language, which was declared extinct after 1990. Others such as Subtiaba, which was most closely related to Me'phaa (Tlapanec), have been extinct longer and are only known from early 20th century descriptions. The Oto-Manguean language family is the most diverse and most geographically widespread language family represented in Mesoamerica. The internal diversity is comparable with that of Indo-European, and the Proto-Oto-Manguean language is estimated to have been spoken some time before 2000 BCE. This means that at least for the past 4000 years Oto-Manguean languages have coexisted with the other languages of Mesoamerica and have developed many traits in common with these, to such an extent that they are seen as part of a sprachbund called the Mesoamerican Linguistic Area. However Oto-Manguean also stands out from the other language families of Mesoamerica in several features. It is the only language family in North America, Mesoamerica and Central America whose members are all tonal languages. It also stands out by having a much more analytic structure than other Mesoamerican languages. Another typical trait of Oto-Manguean is that its members almost all show VSO (verb–subject–object) in basic order of clausal constituents. Overview History of classification Internal classification and reconstruction A genetic relationship between Zapotecan and Mixtecan was first proposed by Manuel Orozco y Berra in 1864; he also included Cuicatec, Chocho and Amuzgo in