The predominant themes of Southeast Asian arts have been religion and national history. In religion the main interest was not so much in actual doctrine but in the life and personality of the Buddha and the personalities and lives of the Hindu gods. In national history the interest was in the legendary heroes of the past, and this theme appeared only after the great empires had fallen and the memories of their glory and power remained. The Buddha image, which went through various stages of development, remained the favourite motif of sculpture and painting. The depiction of scenes from his previous lives in fresco and relief sculpture also had the purpose of teaching the Buddhist ethics to the people, as the Jatakas emphasized certain moral virtues of the Buddha in his previous lives; it also gave an opportunity to the artist to introduce local colour by using, as background, scenes from his own contemporary time. The depiction of scenes from the Hindu epics also had the same purpose and gave the same opportunity to the artist. Many figures from the Buddhist and Hindu scriptures, such as gods and goddesses, heroes and princesses, hermits and magicians, demons and dragons, flying horses and winged maidens, became fused with similar native figures, and, gradually, folklore plots became merged in the general religious themes.

The naga, a superhuman spirit, was taken from Buddhist and Hindu texts and merged with native counterparts, with the result that different images of the naga appeared in various regions. The Burmese naga was a snake with a crested head. The Mon naga was a crocodile, and the Khmer and Indonesian naga was conceived as a nineheaded snake. The demons of various kinds from all over Southeast Asia became merged under one name of Pali-Sanskrit origin, yakkha or yaksha, but they retained their separate identities in sculpture and paintings of their own different countries. The lion, which was unknown to the monsoon forest but was a figure of Hindu and Buddhist mythology, evolved into a native symbol and art motif. The worship of the snake-dragon as a god of fertility was retained in the Khmer empire; the nineheaded naga became a symbol of security and of royalty, and stone nagas guarded the palaces and temples. Buddhism frowned upon naga worship. In Burmese and Mon sculpture the naga was always shown as a servant of the Buddha, putting his body in coils to make a seat for his master and raising his great hood as an umbrella over his master’s head. According to tradition, the guardian figure of a Mon temple was a two-bodied lion with a man’s head, and the guardian figure of a Burmese temple was the crested lion. The Tai made themselves heirs to both the Khmer and the Mon art traditions relating to the naga, but the guardian figure of their temples was the benevolent demon.

Ancient symbols and animal imagery merged with Indian animals and entered the arts. The Pyu embossed the symbol of the sun on their coins as insignia of their power, and the Burmese transformed it into their favourite bird, the peacock, on the excuse that Buddhist mythology associated the peacock with the sun; the Mons adopted the red sheldrake as their symbol, and in Indonesia the mythical bird called Garuda, the vehicle of Vishnu, became merged with the local eagle. The figures of these birds also became decorative motifs. Animals of the Southeast Asian forests whose figures had adorned dwellings of wood and thatch were stylized and came to adorn palaces and monasteries. Ancient geometrical patterns mixed with new spirals and curves from India, and Indian floral designs merged with those of trees and fruits and flowers copied from the monsoon forests.