Jayavarman VIII (Khmer: ជ័យវរ្ម័នទី៨) was a Shaivite, reverting the Angkor empire to Hinduism from his father's religion of Buddhism, and patronised Hinduism throughout his reign.
He is often said to be responsible for initiating an iconoclastic campaign, during which most of Angkor’s Buddha images were defaced or destroyed, but I am not so sure – for my thoughts on this matter see The Hindu Reaction.
During his reign, the Mongol troops of Kublai Khan (Yuan Dynasty) threatened the empire from the north and east, having invaded neighbouring Vietnam (Chen Dynasty). Jayavarman VIII did not wage war with the Mongols, wisely choosing to pay tribute, thereby preserving the empire. Chinese annals record that in 1291, "the king of Lohu" [Cambodia] sent a mission who presented “the usual tribute of gold, elephant ivory and other things”.
Jayavarman VIII also suffered increasing pressure from the west, culminating in a devastating war against the Sukhothai Kingdom.
In 1295, Jayavarman VIII dedicated the Hindu shrine East Top Temple (Mangalartha), the last dated temple to be built in Angkor.