Following the reign of Queen Jayadevi, Chenla gradually splintered, entering a period of political disarray that lasted nearly a century. The unification of the Khmer states began under Jayavarman II (r. 802–835), originally a noble or minor ruler from southeastern Cambodia. Jayavarman, along with his followers, journeyed northwest across the land, consolidating control over former Funanese centers such as Vyadhapura and Banteay Prei Nokor, and forming key alliances. Eventually, they arrived in the Angkor region, where Jayavarman proclaimed himself devaraja, or “god king,” at Phnom Kulen in 802 AD. He established a new capital at Hariharalaya (also known as Yasodharapura, near present-day Roluos), marking the beginning of what would become the Angkor Empire. The name Angkor derives from the Sanskrit word nagara, meaning “city.”

Through Jayavarman’s efforts, numerous independent Khmer polities were united into a cohesive kingdom, known as Kambujadesa. Angkor became Cambodia’s first and only empire, extending from southern Vietnam and the South China Sea to encompass much of modern Thailand, parts of Myanmar, and Laos. At its height, Angkor was a marvel of its era, with a population estimated at over one million, spread across an area exceeding 1,000 square kilometers.

Over the next six centuries, 28 kings succeeded Jayavarman II, each considered a divine ruler despite frequent challenges to their reigns. Angkorian kings engineered vast reservoirs and complex hydraulic systems, enabling up to four rice crops per year and supporting a growing population of nobles, priests, and thousands of laborers tasked with constructing the empire’s elaborate temples. An extensive network of roads connected the empire, with stone causeways crossing floodplains and rest houses placed along routes. Supported by an efficient army bolstered by local peasants as needed, Angkor managed to defend itself against powerful neighboring Cham and Thai states, securing its legacy as a remarkable and resilient civilization.