The history of Cambodia, a country in mainland Southeast Asia, can be traced back to Indian civilization. Detailed records of a political structure on the territory of what is now Cambodia first appear in Chinese annals in reference to Funan, a polity that encompassed the southernmost part of the Indochinese peninsula during the 1st to 6th centuries. Centered at the lower Mekong, Funan is noted as the oldest regional Hindu culture, which suggests prolonged socio-economic interaction with maritime trading partners of the Indosphere in the west. By the 6th century a civilization, called Chenla or Zhenla in Chinese annals, firmly replaced Funan, as it controlled larger, more undulating areas of Indochina and maintained more than a singular centre of power.
The Khmer Empire was established by the early 9th century. Sources refer here to a mythical initiation and consecration ceremony to claim political legitimacy by founder Jayavarman II at Mount Kulen (Mount Mahendra) in 802 CE. A succession of powerful sovereigns, continuing the Hindu devaraja cult tradition, reigned over the classical era of Khmer civilization until the 11th century. A new dynasty of provincial origin introduced Buddhism, which according to some scholars resulted in royal religious discontinuities and general decline. The royal chronology ends in the 14th century. Great achievements in administration, agriculture, architecture, hydrology, logistics, urban planning and the arts are testimony to a creative and progressive civilisation - in its complexity a cornerstone of Southeast Asian cultural legacy.
The decline continued through a transitional period of approximately 100 years followed by the Middle Period of Cambodian history, also called the Post-Angkor Period, beginning in the mid 15th century. Although the Hindu cults had by then been all but replaced, the monument sites at the old capital remained an important spiritual centre.
Yet since the mid 15th century the core population steadily moved to the east and – with brief exceptions – settled at the confluence of the Mekong and Tonle Sap rivers at Chaktomuk, Longvek and Oudong.