Serfs and slaves accounted for 95 percent of the Tibetan population (peasants 60%, herdsmen 20%, and lower-class monks 15%). They were owned by serf-owners, just like the means of production. They had no political rights or personal freedom. They and their children were freely given away as gifts of donations, sold or exchanged for goods. Their marriages had to be approved in advance by their manorial lords. Serfs who married out of the manorial estate had to pay ransom money to their lords. Those who could not perform corvee or went out to seek a livelihood elsewhere should pay “corvee taxes” to show their dependence on the lords. If a serf lost his ability to work, his thralkang field, livestock and farm tools would be those who died without issue was confiscated.

    (Source: tibet.cn)