This map of Southeast Asia in the mid-16th century shows the major centers of power in the region prior to the arrival of Europeans. During this period, these kingdoms were constantly at war. Eventually the Kingdom of Ayutthaya (modern Thailand) expanded to the north and east, absorbing much of Lan Na and Lan Xang (modern Laos). Dai Viet (modern Vietnam) expanded to the south, taking over the remaining territory of the Kingdom of Champa and the southern tip of the Kingdom of Lovek (modern Cambodia). Toungoo evolved into modern Myanmar.
The four centuries of Cambodian history following the abandonment of Angkor are poorly recorded, and therefore historians know little about them beyond the bare outlines. Cambodia retained its language and its cultural identity despite frequent invasions by the powerful Thai kingdom of Ayutthaya and incursions by Vietnamese forces. Indeed, for much of this period, Cambodia was a relatively prosperous trading kingdom with its capital at Lovek, near present-day Phnom Penh. European visitors wrote of the Buddhist piety of the inhabitants of the Kingdom of Lovek. During this period, Cambodians composed the country's most important work of literature, the Reamker (based on the Indian myth of the Ramayana).
In the late 18th century, a civil war in Vietnam and disorder following a Burmese invasion of Ayutthaya spilled over into Cambodia and devastated the area. In the early 19th century, newly established dynasties in Vietnam and Thailand competed for control over the Cambodian court. The warfare that ensued, beginning in the l830s, came close to destroying Cambodia.