Answer: Polyandry
Explanation:
There are lots of families in Tibet practice this Polyandry.
Especially fraternal Polyandry.
Polyandry is a type of marriage system whereby a woman has more than one husband. In Tibet, a woman can marry more than 2 men. Tibet commonly practice fraternal Polyandry where a woman marries more than one blood brothers. This is done in Tibet so that women will have a lot of assistants on their farms due to difficult and strong land topography and terrains and also to settle inheritance issues among siblings especially in land cases.