Angkor is the main focus of foreign visitors to Cambodia, but Khmer empire included parts of today's Thailand, Vietnam and Laos. Although the Khmer empire may have started in the third century, a second Indian migration to Funan province took place at this time, and the sage Kaundinya who cam to Funan, set out to rule the country, after he married princess Soma, the daughter of Naga king. Sanskrit became the official language of the Funan kingdom, which continued till the fourteenth century. He also introduced the worship of God Shiva in his kingdom. King Jayavarman (Kaundinya-Jayavarman) (480 - 514 A.D) and his son Rudravarman were notable kings of Khmer empire, and the list also includes Jayavarman II (802 A.D) with a succession of kings all the way to Jayavarman VIII (1270 A. D.) and Srindrajayavarman (1307 A. D.)
The ruins of cities and sanctuaries of Khmer Empire from fifth to thirteenth centuries have been meticulously studied by the author and photographically illustrated with spectacular and breathtaking aerial views. The views of Phanom Bekheng (page 105), built by Yashovarman I in his new capital Yashodapura which has 108 small shrines (108 is a sacred number in Vedic cosmology); Pre Rup (Page 140) built in 926 AD; Prang, the highest mountain temple in the Khmer empire (page 120, 123); Angkor Wat (from the Sanskrit word, nagara (city)), the apotheosis of Khmer architecture (page 215), and Preah Vihar (pages 149, 151 and 160) are simply wonderful archeological masterpieces. The general plan of the Angkor covers about 500 sq kilometers over a period of five centuries, an almost uninterrupted succession of supreme kings who built their capitals, each centered on a state temple; Bakong, Phanom Bakheng, Pre Rup, Ta Keo, Phimea Nakas, Bapoun, Angkor Wat and Bayon. Three faiths were practiced in ancient Cambodia. They were Hinduism in the form of Shiva, and Vishnu worship and Buddhism.
The Vedic gods have largely vanished from the temples of India but the deities of rgvedic period may be found in many temples of Khmer Empire. The statue of God Surya at Prasat Thom (page 112) built before 921 A.D. Prasat Bak, the only Khmer temple dedicated to the worship of Ganesha; The statue of God Yama, the king of death in the central sanctuary of Banteay Pichiea (page 126); The statues of wrestling monkey kings, Sugriva and Valin at Prasat Chen is an episode from Ramayana, is found on page 128. God Varuna, borne on three hamsas at Muang Tan (page 166), and the structure of Muang Tan (pages 165-167) are simply great. Other statues of interest are; Krishna Govardhana statue from Wat Koh of Takeo province (late 6 and early 7 century) beautifully depicts God Krishna lifting the mount Govardhana to protect his flock from rain created by Vedic God Indra (page 46); Durga from Tuol Komnop (7 century)(page 47) and the standing Buddha from Tuol Lean and Angkor Borei (7 century) (page 50) illustrates fine workmanship of Khmer people.
The oldest inscriptions engraved in a script in Sanskrit dates back to fifth century and they all relate to Hindu and Buddhist temples. Unfortunately all ancient manuscripts have been lost or destroyed, but all Southeast Asian alphabets originated from Sanskrit, which was largely used to honor Vedic gods and communication among literary elite.
The temples of Khmers were different from Christian and Jewish places of worship. They were never designed as meeting places, but as dwellings of gods. They were generally made of durable materials; brick, sandstone, or laterite. The central sanctuary of Ankor Wat, one of the largest is only five square meters, and the sheer size of the temples in the 12 and 13 centuries is ascribed to accommodate large numbers of gods. Fire sacrifice, as in India, was commonly practiced in Khmer temples; the fire had to be ceremonially rekindled each morning before the ceremonial worship of the main deity and cooked food were offered to the god. They were symbolically consumed by gods and then distributed to devotees present at these rituals. Once a year, the solemn feast of god was celebrated with great ceremony and the deity was carried around the temple in a procession atop a chariot. This practice is still popular in India.
The history of the Khmer Empire has been briefly described in this book; this is by no means an academic discussion, but for a traveler interested to visit these places of ancient history, this is sufficient. The photographs and brief description of the history of the temples and the deities are helpful in choosing what you would like to see during your visit to Cambodia and Thailand.