Archaeological data supports the theory that during the Neolithic period (7000 to 2000 BCE) in China, Chinese matrilineal clans evolved into the usual patrilineal families by passing through a transitional patrilineal clan phase. Evidence includes some "richly furnished" tombs for young women in the early Neolithic Yangshao culture, whose multiple other collective burials imply a matrilineal clan culture. Toward the late Neolithic period, when burials were apparently of couples, "a reflection of patriarchy", an increasing elaboration of presumed chiefs' burials is reported.