The Tibetans speak the Tibetan language natively and form one of the 56 ethnic groups officially recognized by the People's Republic of China (PRC), although in anthropological terms they include more than one ethnic group. According to an official census of 1959, the number of Tibetans in the PRC was 6,330,567  (http://www.tibet.com/WhitePaper/white8.html). Tibetans are one of the four non-Chinese nations incorporated into the PRC, the others being the Uighur, the Manchu and the Mongols. The SIL Ethnologue documents an additional 125,000 Tibetan language speakers living in India, 60,000 in Nepal, and 4,000 in Bhutan.
Tibetans generally observe Tibetan Buddhism and a close affiliate known as Bön.
It is generally agreed that Tibetans share a considerable genetic background with Mongols, although other main influences do exist. Some anthropologists have suggested an Indo-Scythian component, and others a Southeast Asian component; both are credible given Tibet's geographic location. (The romantic claim that American Hopi and Tibetans are close cousins is not likely to find support in genetic studies although strong cultural similarities may be found between the two groups).
Tibetans traditionally explain their own origins as rooted in the marriage of the bodhisattva Chenrezig and a mountain ogress. Tibetans who display compassion, moderation, intelligence, and wisdom are said to take after father, while Tibetans who are "red-faced, fond of sinful pursuits, and very stubborn" are said to take after mother.
There are two main ethnic groups in Tibet, in addition to the Han Chinese moved there in recent years by the PRC government. Central Tibetans (those living in the vast area around Lhasa, Ü-Tsang) obviously share a strong Mongolian component in their ancestry, whereas the tent-dwelling nomads of the high Tibetan plateau (known as Drokpa, in Tib. Hbrog-pa, "steppe-dwellers") and the "Khambas" in Kham are by comparison taller and longer-limbed, with sharper features and more aquiline noses. Some have suggested they are of Scythian descent. The Eastern Tibetans are not as mixed as the Central Tibetans in the sedentary areas. In Western Tibet, in the border lands to Ladakh and Kashmir, people are often of Indo-Aryan descent.
Since the late 19th century, Chinese presence in Eastern Tibet has increased and often the Khambas there are bilingual. Still, mixed marriages between Tibetans and Chinese were not common.
Tibetans typically have light brown skin, black, somewhat wavy or even curly hair, moderately high cheekbones, and brown eyes, although some have very light hazel and green eyes, due to their Mongol heritage. The men typically have full mustaches but sparse beards; traditionally, they pluck out their beards with tweezers. Nomads have long braided hair, the women usually braid their hair in 108 braids.
Tibetans have a legendary reputation to be able to survive extremes of altitude and cold, abilities which were no doubt conditioned by the extreme environment of the Tibetan plateau. Recently scientists have sought to isolate the cultural and genetic factors behind this adaptability (http://www.cwru.edu/affil/tibet/HAN.html). Among their findings: a gene which improves oxygen saturation in hemoglobin, and also a study that found that Tibetan children grow faster than other children to the age of five (presumably as a defense against heat loss since larger bodies have a more favorable surface to volume ratio). The Tibet Paleolithic Project (http://paleo.sscnet.ucla.edu/TibetGroupPage.html) is studying the Stone Age colonization of the plateau, hoping to gain insight into human adaptability in general and the cultural strategies the Tibetans developed as they learned to survive in this harsh environment.
The 1911 Encyclopædia Britannica reported that "among the customs of the Tibetans, perhaps the most peculiar is polyandry, the brothers in a family having one wife in common. Monogamy, however, seems to be the rule among the pastoral tribes, and polygamy is not unknown in Tibet, especially in the eastern parts of the country." An article by Melvyn C. Goldstein in the March, 1987 issue of Natural History (the magazine of the American Museum of Natural History) discusses Tibetan fraternal polyandry and confirms the continuation of this practice into recent times.  (http://www.cwru.edu/affil/tibet/family.html)
- This article incorporates text from the public domain 1911 Encyclopædia Britannica.