Indravarman I

With Indravarman I, who took the throne at Hariharalaya in 877, the Khmer kingdom enters a period documented by substantial contemporary inscriptions rather than later tradition. His connection to his predecessor Jayavarman III was indirect — he appears to have claimed legitimacy through marriage and through descent from regional ruling families — and his own inscriptions emphasize personal merit, boasting that he gained his position without conventional rivals.

Indravarman's reign established the template that organized Khmer royal building for centuries. He began with a hydraulic project, the Indratataka, a reservoir at Hariharalaya measuring roughly 3.8 kilometers by 800 meters, the first of the great barays. He followed it in 879 with Preah Ko, a temple dedicating six brick tower-shrines to his royal and parental ancestors, including Jayavarman II. In 881 he consecrated the Bakong, a stepped pyramid of sandstone-faced terraces crowned by a lingam called Indreshvara, fusing the king's name with Shiva's. The Bakong is the earliest surviving large temple-mountain in the Khmer tradition and the architectural ancestor of Angkor Wat.

The sequence — reservoir, ancestor temple, state temple-mountain — was more than a building program. The baray anchored the agricultural and ritual landscape, the ancestor shrine secured the king's genealogical claims, and the temple-mountain identified his reign with the cosmic order. Nearly every major Angkorian ruler after Indravarman repeated some version of this pattern.

Indravarman also extended Khmer authority outward; inscriptions suggest influence reaching into the Mun River basin of present-day northeast Thailand, though the nature of such control at this date was probably loose overlordship rather than direct administration. He died around 889 and received the posthumous name Ishvaraloka. The succession passed to his son Yasovarman I, apparently after a contested interval that some scholars infer from references to fighting in later texts, and it was the son who moved the capital from Hariharalaya to the site that would bear the dynasty's name.