Indochina

In the 1st through 5th centuries, most of southeast Asia was dominated by Funan, which included most of present Thailand, Laos, Cambodia and the Mekong delta region of Vietnam. Funan was supplanted around the 6th century by Chenla. Annam was a small coastal strip in north Vietnam and southern China, and south of it Champa controlled a coastal strip in central Vietnam.

Pressure from China pushed Annam southwards, and in turn Annam pushed Champa south to roughly modern central South Vietnam. Around the 12th century the Khmers emerged as a great empire controlling all the lower Mekong, leaving Sukhothai as a small version of modern Siam and Laos. The Khmer Empire collapsed after Siam seized Angkor in 1431.

The Khmers (Cambodia) thereafter found themselves pinched between their more powerful neighbours Siam and Annam. In the late 18th and early 19th century, much of Cambodia was partiti