Faces representing nearly 700 years of ancient Khmer history (6th-14th centuries AD)
Six hundred years of Khmer kings disguised as gods. All were done during the lifetime of the king. They represent the king as devaraja, god-king, so that the king could be represented as Shiva (the god with a third eye in the middle of the forehead) in a statue in a Shivaite temple, Vishnu (four arms) in another temple, and as Buddha in Buddhist temples (Buddhism was not regarded as a distinct religion).
Devaraja statues had two purposes, to identify the king as the legitimate source of power, derived from the god, and, through copies set up in temples throughout the kingdom, to mark his domains. Hence the need for recognisable portraits – they were identifying individual kings. If the kingdom fractured, as it sometimes did, rival claimants to the throne would set up their own statues, but these would be destroyed when the kingdom was reunified.
The devaraja cult lives on today – the king is still an incarnation of the god Vishnu, which accounts for the popularity of the Vishnu shrine on the Riverfront in front of the Royal Palace in Phnom Penh.
Portrait Statues of the Ancient Cambodian (Khmer) Devaraja or Divine Kings, Smithsonian Tropical Research Institute, 8 January, 2009 (pdf file)