Indravarman’s son and successor, Yaśovarman I (ruled c. 890–c. 910), moved the capital again, now closer to Siĕmréab, to a location that subsequently became Angkor—a name derived from the Sanskrit word nagara, meaning “city”—which has become one of the world’s most-celebrated archaeological sites (as well as a UNESCO World Heritage site), as well as the popular name for Cambodia’s medieval civilization. The city that Yaśovarman founded, Yaśodharapura, retained that name and remained Cambodia’s capital until it was abandoned in the 16th century. His temple mountain, now called Bakheng (literally “Mighty Ancestor”), was built on a natural hill that overlooked a teeming city, the more-distant rice-growing plain, and the Tonle Sap. The mountain occupied the center of the city, just as Mount Meru, the mythical home in India of the Hindu gods, was said to stand at the center of the universe. Yaśovarman built a large reservoir nearby. The city wall of Yaśodharapura measured 2.5 miles (4 km) on each side. For such an ambitious building program, the king needed to command a large labor pool. Other evidence suggests that his reign was characterized by tolerance toward a variety of Buddhist and Hindu sects that occasionally blended into local cults honoring ancestral spirits and spirits of the soil. Indeed, for all the apparent absolutism of its kings, a consistent feature of Angkorean civilization unmatched in medieval Europe was religious toleration.

After several decades of warfare, dislocations, and disorder—Yaśodharapura itself was abandoned for nearly 30 years—Rajendravarman II (ruled 944–968) restored the capital and set in motion a period of peace and prosperity that lasted nearly a century. During the reign of his successor, Jayavarman V (968–c. 1000), the rose-colored sandstone shrine of Banteai Srei—arguably the loveliest temple at Angkor—was built on the outskirts of the capital under the patronage of a wealthy priestly family, one of whose members had been Jayavarman’s teacher. In Yaśodharapura itself, Jayavarman V began work on the imposing temple mountain now called Ta Keo, which was completed under his successor, Suryavarman I (ruled c. 1004–c. 1050). Suryavarman I, an innovative and demanding monarch, was a usurper with links to princely families in what is now northeastern Thailand. His rise to power involved the subjugation of many areas that had become semi-independent under his predecessors, and his reign resembled that of Jayavarman II two centuries earlier. Suryavarman extended the Khmer empire westward into present-day Thailand, where he constructed the large mountaintop temple known as Preah Vihear. During his reign the number of cities ruled from Yaśodharapura grew from roughly 20 to nearly 50, and foreign trade increased, along with tighter central bureaucratic control. His successor consolidated those gains, put down a dangerous rebellion, and was responsible for the temple mountain known today as the Baphuon.

The closing years of the 11th century were ones of turmoil and fragmentation. At different times, two and even three “absolute monarchs” contended simultaneously for the title of chakravartin. At the end of the century, however, a new dynasty—which was to last for more than a century—began to rule at Angkor. Its most powerful monarch took the name of Suryavarman II (ruled 1113–c. 1150), although he probably was not descended from the earlier king of that name. Like his namesake predecessor, Suryavarman II was a formidable military campaigner. He avenged earlier attacks on Angkor by armies launched from the kingdom of Champa, in what is now south-central Vietnam, and led expeditions into northern and southern Thailand. A campaign against Vietnam, which had recently declared its independence from China, was less successful.

Suryavarman’s major accomplishment, from a modern perspective, was the Angkor Wat temple complex, still the largest religious structure in the world and one of the most beautiful. The temple, which eventually became his tomb and probably was an astronomical observatory as well, was dedicated to the Hindu god Vishnu. Its bas-reliefs, running for nearly a half mile inside its third enclosure, depict events in the well-known Indian epics Mahabharata and Ramayana—confirming that those texts were widely known at Angkor—as well as Suryavarman himself holding court. The elegance of the carvings, the hundreds of graceful statues of angelic dancers (apsaras) that adorn the temple, and its reflection in the moats that surround it continue to give Angkor Wat an awe-inspiring air; in the 12th century, when its towers were gilded and its moats properly maintained, it must have been even more breathtaking.