Polyandry

Polyandry is much less common in the world than the other form of polygamy, polygyny, in which a man has two or more wives. In polyandrous households, one wife has two or more husbands. It was a form of plural marriage in resource poor regions.

Now, the NY Times reports, One Bride for 2 Brothers: A Custom Fades in India

In the remote villages of this Himalayan valley, polyandry, the practice of multiple men marrying one wife, was for centuries a practical solution to a set of geographic, economic and meteorological problems.
"People here survived off small farms hewed from the mountainsides at an altitude of 11,000 feet, and dividing property among several sons would leave each with too little land to feed a family. A harsh mountain winter ends the short planting season abruptly. The margin between starvation and survival is slender."...

"Polyandry has been practiced here for centuries, but in a single generation it has all but vanished. "...

"Polyandry has never been common in India, but pockets have persisted, especially among the Hindu and Buddhist communities of the Himalayas, where India abuts Tibet."