1440's (CE) The rulers of the Khmers move the capital of the Khmer Empire to Phnom Penh.
The King was defeated
1593 CE The Siamese (Thai) king attacks and defeats the Khmer king.
Vietnam attacks Khmer
1700's (CE) Vietnamese armies regularly attack the Khmer forces in the Mekong River delta and end up defeating the Khmers. The approximate modern borders of Cambodia are now determined. This is the end of the Khmer Empire.