The site is divided into the temple grounds in the east and the urban centre to the west. The temple grounds are primarily in 3 main clusters, North, Central and South, with some outlying temples that sit outside of the temple groups. Each of the three groups is dedicated to Hindu deities and is surrounded by two walled, non-concentric, rectangular enclosures. The city in the west is surrounded by a moat measuring 2km, surrounding the city on three sides, except for the east side, which is bordered by the seasonal O Krue Ke river. The city itself comprises various shrines, moats, and reservoirs on a smaller scale compared to the religious complexes. Subsequent topographic data based on LIDAR scans suggests a 4x4 grid pointing to a planned layout. An inferred linear feature is believed to be a hydrological feature such as a moat or canal measuring a total of 20 metres in width, consistent with descriptions provided in the
Book of Sui about the so called “Great Hall”, it extends eastward from the centre point of the grid towards the religious complex. Description of the urban layout of Isanapura is also recorded in the Book of Sui, mentioning the western urban centre and the religious complexes located in the east, which thus far match the observations of ongoing archaeological excavation and research. Relative dating of the site itself is difficult due to the lack of evidence, both from the absence of inscriptions and the inscriptions found at Prasat Tao to date. The central shrine of Prasat Tao is believed to have been constructed later, given the implementation of early 9th century Angkor styles. However, it is more likely that the construction was simultaneous with Prasat Yeai Poeun and was finished later. The southern group, Prasat Yeai Poeun, was built during the 7th century, as per 10 inscriptions found, with a specific date of 627 AD on a Linga inscription construction started in the reign of Isanavarman I. The majority of the lintels at Prasat Yeai Poeun are of the Sambor Prei Kuk style and point towards most construction taking place during a relatively short time frame, with only a few outliers of other styles having been found. It is speculated that building at Prasat Yeai Poeun was undertaken continuously from the end of Isanavarman II’s reign to his successor, Bhavavarman II. Recent surveys conducted in the western portion of Sambor Prei Kuk have identified the “Great Hall”, believed to be described in the Book of Sui. The geographic position of the site, located centrally within the identified grid plan, is consistent with that described in Sui records. LiDAR scans and excavations revealed laterite and brick remains of a terrace-like structure running 70 metres north to south and 15 metres east to west, which was subsequently identified along with laterite masonry walls 2.1 metres in height. Square bases of brick spaced at 1.5 metre intervals on all four cardinal directions suggest possible bases for wooden supports and beams. However, the absence of wood and damage to surviving brickwork lacks the supporting evidence to confirm this without any doubt. LiDAR identification of brick structures is spatially arranged, such as the excavation site itself, which is the central point surrounded by these buildings. A cluster of buildings to the east of the terrace may have been guard buildings and associated structures mentioned in the Book of Sui. Radiocarbon dating on the surrounding structures dates their construction to coincide with both Isanavarman I and Bhavavarman II. Other charcoal samples have been radiocarbon dated to the earliest in the early 5th century and the latest in the 13th to 15th centuries, supporting the belief in long term utilisation of the city. ==References==