Identification. The Otomí could have been the original inhabitants of the Valley of Mexico, before the Nahua speakers arrived. Today they are split into two main groups: the Highland Otomí, living mainly to the north of the Valley of Mexico, and a smaller group, the Sierra Otomí, who live in the mountains of eastern Hidalgo and in adjoining parts of the states of Veracruz and Puebla. The Otomí of the Sierra refer to themselves as "Nąñų," meaning " speakers of the Otomí language," or, more formally, as "Nųhų," meaning "Otomí people."
The subgroup of Sierra Otomí who live in and around the village of Santa Ana Hueytlalpan, Hidalgo, are considered by some to be a separate cultural group. Their culture is adapted to the highland environment of the Tulancingo Basin; however, their commercial and social contacts are with the other Sierra Otomí to the east in the mountains, rather than with the Highland Otomí.
Location. In 1990 the Sierra Otomí occupied the area within 20°7′ to 20°46′ N and 97°56′ to 98°27′ W. The environment in which the Sierra Otomí live is varied. Ninetyfour percent of the population live in mountains ranging from 160 to 2,000 meters in elevation. The mountains are steep and folded. Monthly rainfall ranges from 0.5 centimeters in February to 50 centimeters in September at the lower elevations and from 0.6 centimeters to 44 centimeters during the same months at the higher elevations. Temperatures vary from a monthly average of 18° C in December to 28° C in June at the lowest elevations and from 14° C in December to 19° C in March at the highest inhabited elevations. The mountain climate has been classified as (A)C(fm)a(e) in the Köppen system. Natural vegetation ranges from tropical rain forest at the lower elevations to tropical cloud forest at the higher elevations. The natural vegetation has been cut back to make room for villages, fields, and pastures. The remaining 6 percent of the population live in the intermontane plain around the village of Santa Ana Hueytlalpan, Hidalgo, at 2,150 meters, where the rainfall and temperature patterns are quite different.
Demography. In 1990 the Sierra Otomí population (as defined by language) was approximately 40,000. Their populations in the three states where they were located was: Hidalgo, 22,500; Puebla, 6,500; and Veracruz, 11,000.
Linguistic Affiliation. Otomí is a member of the Otopamean Language Family, which is a subfamily of the Otomanguean Language Group. Among the Sierra Otomí there are many dialects, not all of which are mutually intelligible.