Why Khmer Temples ended up in Thailand?

* Phimai Historical Park is an ancient Khmer city of the Khmer Empire in Thailand situated in Phimai District of Nakhon Ratchasima Province and is about 60 kilometers north from Phimai, the Capital. The ancient Khmer city [ and earlier in 7 - 8 C part of Chenla Kingdom ] is surrounded by a moat adjacent to the Mun River on the east and north boundaries. Phimai is the largest Khmer ruins complex in Thailand and comprises an inner moated city, 565 by 1030 metres, which was built in the 11 – 12 C with further additions in the 13 C.

http://www.art-and-archaeology.com/seasia/prung/pr01.html
* The Temple City was surrounded by a laterite wall 3,350 feet by 1,900 feet with the Temple enclosed by two walls, the outer measuring 900 feet by 720 feet and the innermost wall 272 by 243 feet. The complex includes the usual structures, naga terraces, gopuras, pavilions, a library. The key feature is the inner court yard which houses three towers. The central and principal tower was built in 11 – 12 C and is made of sandstone. The outer walls are decorated with lintels and bas-reliefs depicting scenes from the Ramayana, illustrating battles between Ravana and Rama. The southern side has bas-reliefs of Shiva and its interior has bas-reliefs of Buddha, Bodhisattvas and Mara. The Temple is Budhist, not Hindu and was part of the Mahayana school which was prevalent in the Mun Valley from the 7 C onwards.

* Phimai has large and small ponds to represent the oceans. The central sanctuary is enclosed by narrow corridor galleries. Cruciform entrances [ or Gopuras ] are installed at cardinal points. Carvings of Hindu Gods ornament the pediments and lintels of these entrances. Within the sacred area the central tower [ or prang ] culminates in a lotus bulb shaped finial and represents Mount Meru. This is built of sandstone. The Prang is many tiered and rests on a base, which is a tall re-dented cube like structure which itself is set on other re-dented and ascending sandstone platforms. Below the tiers of the tower and set in the cube re-dented base was placed the linga, or phallic emblem of the God Shiva and later a Buddha image.

* The other two towers were built in 13 C. One was made of laterite and the other, of red sandstone. The former houses a large sculpture of King Jayavarman [ of Angkor ] who reigned during its construction. Phimai has similar features to those at Phnom Rung , it has access via a long causeway with terraces, the stone balustrades of which are shaped as serpents or Nagas. These Nagas have multiple flaring heads which are crowned, and act as guardians of the earths' waters and are said to represent the rainbow, the link between the world of men and the Gods. Accordingly when one approaches these sanctuaries [ or Temples ] via these Naga causeways one is reminded that as a devotee he or she is leaving the earthly plan, physically and spiritually, for higher levels of enlightenment.

* Just north of Phimai Historical Park, and not to be missed, is the Phimai National Museum which houses Khmer artifacts and works of art from excavations, not only from Phimai, but other Khmer ruins in southern I 'san. This complex is the most outstanding example of Khmer Architecture in Thailand.

The above text is from: http://www.thailandsworld.com/index.cfm?p=173

Prasat Phnom Rung

Early 12th century

Phnom Rung, on the royal road between Angkor and Phimai, was built early in the reign of Suryavarman II (1112-1152) by Narendraditya, a local ruler and kinsman of the king. The east-facing axial temple is built upon a hill ("phnom" means "hill" in the Khmer language). The temple is approached by a long east-west causeway (160m, or 530') that is lined with lotus-bud posts. The west end of the causeway is seen in this photo, where it abuts a naga bridge like the one at Phimai. Crossing over the platform, one climbs the stairs to reach the temple enclosure.

Phnom Rung was built after Phimai and before Angkor Wat. It has several design features in common with both, particularly the use of naga bridges and the Khmer-type tower pioneered at Phimai. Yet, there is not a sense of progressive development in these three temples; Phnom Rung goes its own way, with a distinct triangular shape to its tower and an antarala (antechamber) between the entrance hall and sanctuary.