The two most populous groups are:
- the Highland (or Sierra) Otomí, living in the mountains of La Huasteca
- Sierra Otomí usually self-identify as Ñuhu or Ñuhmu, depending on the dialect they speak
- the Mezquital Otomí, living in the Mezquital Valley in the eastern part of the state of Hidalgo, and in the state of Querétaro.
Otomi woman selling traditional Otomi embroidered cloths in Tequisquiapan
Smaller Otomi populations exist in the states of Puebla, Mexico, Tlaxcala, Michoacán and Guanajuato. The Otomi language belonging to the Oto-Pamean branch of the Oto-Manguean language family is spoken in many different varieties some of which are not mutually intelligible.
One of the early complex cultures of Mesoamerica, the Otomi were likely the original inhabitants of the central Mexican Altiplano before the arrival of Nahuatl speakers around c. 1000 CE, but gradually they were replaced and marginalized by Nahua peoples. In the early colonial New Spain period, Otomi speakers helped the Spanish conquistadors as mercenaries and allies, which allowed them to extend into territories that had previously been inhabited by semi-nomadic Chichimecs, for example Querétaro and Guanajuato.
The Otomi traditionally worshipped the moon as their highest deity, and even into modern times many Otomi populations practice shamanism and hold prehispanic beliefs such as Nagualism. Otomies traditionally subsisted on maize, beans and squash as most Mesoamerican sedentary peoples, but the maguey (century plant) was also an important cultigen used for production of alcohol (pulque) and fiber (henequen). Although the Otomi Indians rarely eat common foods that are thought necessary to maintain a healthy food pattern they maintain a fairy good diet by eating tortillas, drinking pulque, and eating most fruits available around them. In 1943 to 1944, a report about a nutritional study about the Otomi villages located in the Mezquital Valley of Mexico, recorded that despite the arid climate and land unfit for agriculture without irrigation the Otomi people chiefly depended on the production of maguey. Maguey (century plant) is used to produce weaving fibers and “pulque” a fermented unfiltered juice, which played an important part in the Otomi’s economy and their nutrition; however, this practice has begun to diminish due to its new large-scale production. The maguey plant was so heavily depended on that huts were constructed out of the plants leaves. During this time, most of the region was vastly underdeveloped and most crops had a very low-yield rate. Settlement areas at times would be confused as locations remote of habitation.
The Otomi were blacksmiths and would trade valuable metal items with other indigenous confederations, including the Aztec Triple Alliance. Some of their metal crafts included ornaments and weoponary; although metal weaponry was not as useful as obsidian weaponry, obsidian is sharper than a modern-day razor, abundant, and light in weight.