Chenla or Zhenla (Chinese: 真臘; pinyin: Zhēnlà; Wade–Giles: Chen-la; Khmer: ចេនឡា, Chénla, Vietnamese: Chân Lạp) is the Chinese designation for the successor polity of the kingdom of Funan preceding the Khmer Empire that existed from around the late 6th to the early 9th century in Indochina. The name was still used in the 13th century by the Chinese envoy Zhou Daguan, author of The Customs of Cambodia. It appears on the Mao Kun map. However, modern historiography applies the name exclusively to the period from the late 6th to the early 9th century. This period of Cambodian history is known by historians as the Pre-Angkor period. It is doubted whether Chenla ever existed as a unitary kingdom, or if this is a misconception by Chinese chroniclers. Most modern historians assert that "Chenla" was in fact just a series of loose and temporary confederations of principalities in the pre-Angkor period.