The Khmer Empire was outside of Southeast Asia.
The Khmer Empire , officially the Angkor Empire , the predecessor state to modern Cambodia ( `` Kampuchea '' or `` Srok Khmer '' to the Khmer people ) , was a powerful Hindu-Buddhist empire in Southeast Asia . The empire , which grew out of the former kingdoms of Funan and Chenla , at times ruled over and/or vassalised most of mainland Southeast Asia .