Constructed more than two centuries before Angkor Wat, Phnom Bakheng was in its day the principal temple of the Angkor region, historians believe. It was the architectural centerpiece of a new capital, Yasodharapura, that Yasovarman built when he moved the court from the capital Hariharalaya in the Roluos area located to the southeast.
An inscription dated 1052 AD and found at the Sdok Kak Thom temple in present-day Thailand states in Sanskrit: "When Sri Yasovardhana became king under the name of Yasovarman, the able Vamasiva continued as his guru. By the king's order, he set up a linga on Sri Yasodharagiri, a mountain equal in beauty to the king of mountains. Scholars believe that this passage refers to the consecration of the Phnom Bakheng temple approximately a century and a half earlier. Phnom Bakheng is one of 3 hilltop temples in the Angkor region that are attributed to Yasovarman's reign. The other two are Phnom Krom to the south near the Tonle Sap lake, and Phnom Bok, northeast of the East Baray reservoir.
Surrounding the mount and temple, labor teams built an outer moat. Avenues radiated out in the four cardinal directions from the mount. A causeway ran in a northwest-southeast orientation from the old capital area to the east section of the new capital's outer moat and then, turning to an east-west orientation, connected directly to the east entrance of the temple.
Later in its history, Phnom Bakheng was converted into a Buddhist temple. A monumental Sitting Buddha, now lost, was created on its upper tier. Across its west side, a Reclining Buddha of similar scale was crafted in stone. The outlines of this figure are still visible.