His reign's monumental architecture, numerous military campaigns and restoration of strong government have led historians to rank Suryavarman II as one of the empire's greatest rulers.

“At the end of his studies,” states an inscription, “he approved the desire of the royal dignity of his family.” He appears to have dealt with a rival claimant from the line of Harshavarman III, probably Nripatindravarman, who held sway in the south, then to have turned on the elderly and largely ineffectual king Dharanindravarman I, his great uncle.

Inscriptions record that the new monarch studied sacred rituals, celebrated religious festivals and gave gifts to the priest such as palanquins, fans, crowns, buckets and rings.

The priest embarked on a lengthy tour of temples in the empire, including the mountaintop Preah Vihear, which he provided with a golden statue of dancing Shiva.

Varman is the traditional suffix of the Pallava dynasty that is generally translated as "shield" or "protector", and was adopted by Khmer royal lineages.

Dvaravati began to come under the influence of the Khmer Empire and central-southeast Asia was ultimately invaded by King Suryavarman II in the first half of the 12th century.

But while Khmer troops gathered in Nghe An (in southern Dai Viet), they faced widespread diseases and pandemics, and so retreated just before the invasion.

Another embassy visited in 1120; in 1128, the emperor conferred high dignities on the Khmer ruler, deeming him “great vassal of the empire.” Problems concerning commerce between the two states were examined and regulated.

He presided over the construction of Angkor Wat,[15]: 372, 378–379  the largest temple ever built in the capital, and in many modern minds the ultimate masterpiece of Khmer architecture.

It was resplendent with more than 1,860 carved apsara, or heavenly nymphs, and hundreds of meters of elaborate bas-reliefs depicting the Hindu legends and scenes from contemporary life.

Other temples dating to his reign include Banteay Samre, Thommanon, Chau Say Tevoda, Wat Athvea and, east of the capital, the huge Beng Mealea complex.

A bas-relief in the south gallery of Angkor Wat shows him seated on an elaborate wooden dais whose legs and railings are carved to resemble naga snakes.

Commanders with armor and weapons stand atop fierce war elephants, with ranks of foot soldiers below, each holding a spear and shield.

[9]: 118 A modern sculpture that adapts his court image in the Angkor Wat bas-reliefs today greets visitors arriving at the Siem Reap airport.