When Tashi Sangmo was 17 she married a 14-year-old neighbour in a Himalayan village in Nepal and as part of the package she also agreed to wed his younger brother. In ancient times, the sons of almost every family in the region of Upper Dolpa, 500 kilometres from the capital Kathmandu, would jointly marry one woman but the practice of polyandry is dying out as the region begins to open up to modern life. "Things are easier this way because everything we have stays in one family. It doesn't get divided among many wives and it is me in charge," said Sangmo, who uses a dialect of Tibetan and was speaking through an interpreter. "Two brothers bring in the money and it's me who decides what to do with it." When Sangmo wed Mingmar Lama 14 years ago, it was understood that her spouse's brother Pasang - then 11 - would later join the relationship in an old practice that persists in only a few isolated Himalayan villages. Between them, they now have three sons aged eight, six and four. "I wanted to share this bond with my brother because life would be easier for both of us," said Pasang, 25, speaking at the family home in Simen village, 4,000 metres above sea level and five days' walk from the nearest town. Traditionally part of the caravans that plied the route between Nepal and Tibet, the people of Upper Dolpa still follow the trade, leading yaks that bring salt from Tibet and rice from the southern Terai plains. In the thin air high above the tree line, arable land is in short supply and farms are tiny. But polyandry prevents the practice of each generation of a family dividing their holdings, and food supplies just manage to cover the locals' basic needs. Marriages are typically arranged, with a family picking a wife for their oldest son and giving the younger brothers the chance to wed her later. In some cases the wives will even help raise their future husbands, entering into sexual relationships with them when they are considered mature enough. Husbands in polyandrous marriages handle domestic duties, helping with cooking and childcare, while women are in charge of the money. Shitar Dorje, 30, married her 37-year-old husband Karma a decade ago. Karma's younger brother Pema entered into the marriage a few years later after finishing studies in Buddhist philosophy. "If it ever happens that we are all in the house at the same time, then my elder brother sleeps with my wife," said Pema, 30. "In my case there is no jealousy. I don't feel bad about the fact that when my brother is in the house our wife is with him. If I felt jealousy, then I would go and marry someone else." Polyandry works well where there is a division of labour between brothers - one to look after livestock, one to help the wife in the fields and one to join the trade caravan. Many also see it as a kind of life assurance, highlighting the added security for women of an arrangement which means they will not be left alone if one husband dies. According to Dutch charity SNV, which has well-established links to the area, life expectancy in Upper Dolpa is 48 for men and 46 for women. Thajom Gurung, 60, from Saldang village, lost her husband Choldung to cancer about 30 years ago. But she was already married to both of his older brothers and now lives with the one surviving sibling, Choyocap, 67. "When we were all together in the house we had turns sharing the bed with my wife - no one worried about it," Choyocap said. SNV says that while 80 percent of households practised polyandry a generation ago the figure is now down to about one in five. "Polyandry is about keeping family together when life is hard," said Choyocap Gurung.