In Tibet, the monogamous households are the land-slide majority. Yet there are some polygynous and polyandrous households in some areas, which seem to be very strange to us outsiders, but have survived for ages as remains of the communal marriages in ancient times. In old Tibet before 1951, many aristocrat households practiced polygyny, through which they could extend their sphere of political and economical influence and thus consolidate their wealth and status. In these cases, the wives used to come from different manors in rural areas, or tribes, in pastoral areas. Some ordinary households also exercise polygyny. In there households, the husband marries a wife at first, then he co-inhabits with his wife's sister, establishing a de-facto marriage bond. In this case, the sisters share the only husband with equal and indiscriminate position. This will not arouse any gossip or reproach, because it seams to be quite normal to the local people.

In contrast to the polygyny, there are also some polyandrous households. In these households, usually the brothers share the only wife, while in a few cases; the friends share the only wife. It is so established that the elder brother marries a wife and then the latter co-inhabits with her husband's younger brother. Just like the polygyny, these practices also are accepted and beyond and reproach.

The survival of the polygyny can be attributed at the economic situations. For example, in Qamdo Prefecture, the polygyny is encouraged just for preserving a kind of clan system so-called 慞abtso? which is formed based on the paternal strain and thus attaches importance to the male offspring, since it is essential to enlarge the clan network, and keep its property from outflowing. Under such circumstances, the husband urges his wife to bear a boy. If the wife fails, the husband will marry the next and the next. That is how the polygynous households emerged. Some husbands even have up to six wives. The wives are considered no more than a breeding instrument without any family or social status. A boy-delivering wife will have superior status to a girl-delivering wife. It is at this point that it is similar to Chinese Han people of some areas.

The existence of the polyandry can also be attributed to the economic reasons. In old Tibet before 1951, paying tax or laboring in lieu of paying tax was effected by using individual households as the basic units. The polyandrous household can either keep the family property from scattering, or relieve the family burdens, thus being viewed by people in some areas as an ideal family. In addition, the wife of such family is also considered a virtuous lady, since she is able to live and get along with several husbands. Until now, in some areas, such as the pastoral area in Chagyab County, the polyandrous households are still much more numerous than the monogamous ones. The polyandrous family is also economically better off than the latter, since the laborers of the monogamous family are fewer, but the children are not necessarily fewer than of the polyandrous. This encouragers the existence of the polyandrous households.