The Yis are monogamous, living in nuclear families. Before liberation in 1949, marriages were generally arranged by parents, and the bride's family often asked for heavy betrothal gifts. In many places, married women stayed at their own parents' home till their first children were born. In some other places, feigned "kidnapping of the bride" was practiced to add to the joyous atmosphere. The groom's family would send people to the bride's home at a prearranged time to snatch the girl and carry her home on horseback. The girl was supposed to cry aloud for help, and her family members and relatives would pretend to chase after the kidnappers. In other cases, when people from the groom's side went to fetch the bride, her people would first "attack" them with water, cudgels and stove ashes, then treat them to wine and meat after a frolic scuffle, and finally let them take the bride away on horseback. On the wedding night, there would also be frolic fighting between the bride and the groom as part of the ceremony. These were obviously legacies of primitive marriage conventions.
Patriarchal and monogamous families were the basic units of the clans in the Liangshan Mountains. When a young man got married, he built his own family by receiving part of his parents' property. Young sons who lived with their parents could get a larger portion of the property. There were rigid differences between sons by the wife and those by concubines in sharing legacies. Property handed down from the ancestors usually went to sons by the wife.
The Yis traditionally associated the father's name with the son's. When a boy was named, the last one or two syllables of his father's name would be added to his own. Such a practice made it possible to trace the family tree back for many generations. In the Yi families, women were in a subordinate position with no right to inherit property, but the remnants of matriarchal society could still be seen clearly sometimes. The Yis much respected the power of uncles on the mother's side, and relations between such uncles and nephews were close. Slaves' marriages and homemaking were in the hands of slaveholders. The fate of slave girls was even more wretched, and they were forced to marry just to meet the needs of slaveowners for more slaves.