Yii'ua

Xi'an Lines or Houses are the genetic heritages of the Xi'an. Careful tracking of one's Yii'ua is mandatory on official public documents, private contracts, etc. in the Xi'an Empire, because the lines are everything to the Xi'an. It's rude to dwell on genetic provenance in polite society. These matrilineal dynasties exist as great Houses, both metaphorically and physically as they grow into great estates and form mega-corporations when they prosper. The only person who is named directly with a Line name is the Emperor.