The name of the territory was also used to refer to the Lac people and their ancient language. It seems to be a Yue or Viet endonym of uncertain meaning, although it has had various folk etymologies over the years. A Chinese geographer, Fan Chengda (1126–1193), explained that the Vietnamese have crossed toes, which meaning jiaozhi in Chinese. In his "Tongdian", Du You (735–812) wrote that "The Jiaozhi are the southern people: the big toe points to the outside of the foot, so if the man stands up straight, the two big toes point to each other, so people call them the "jiaozhi"." (The Chinese character means "hallux, big toe".) The "Ciyuan" disputed this: Various Vietnamese scholars such as Nguyễn Văn Siêu and Đặng Xuân Bảng have since echoed this explanation.