In a mist-shrouded valley on China's invisible border with Tibet is a place known as the 'Kingdom of Women'. A small tribe called the Mosuo lives in a cluster of villages that have changed little in centuries.This is one of the last matrilineal societies on earth, where power lies in the hands of women.All decisions and rights related to money, property, land and the children born to them rest with the Mosuo women, who live completely independently of husbands, fathers and brothers, with the grandmother as the head of each family.A unique practice is also enshrined in Mosuo tradition - that of 'walking marriage', where women choose their own lovers from men within the tribe but are beholden to none. Choo WaiHong, a corporate lawyer, yearned for escape and ended up living in Mosuo for six years - the only non-Mosuo to have ever done so.She tells the story of the remarkable story of her time in the remote mountains of China and gives a vibrant, compelling glimpse into a way of life that teeters on the knife-edge of extinction.