[1]: 8–9 Under the reign of the kings Jayavarman IV and Harshavarman II Koh Ker was briefly the capital of the whole empire (928–944 AD).

Coming from Angkor and Beng Mealea to Koh Ker this road led to Prasat Preah Vihear and from there to Phimai in Thailand and Wat Phu in Laos .

Some historians think that Jayavarman IV was a usurper; but, the majority of them believe that he was a legitimate ruler who could ascend to the throne because he married a half-sister of king Yasovarman I (889 – 900).

In the short time that Jayavarman IV reigned in Koh Ker, an ambitious building program was realised.

[1]: 15 Even after 944, as the capital of the Khmer Empire had changed back to the plains north of the Tonle Sap-lake, more temples were built at the site of Koh Ker.

[1]: 15  [1]: 25 In the second part of the 19th century, French adventurers ranged the forests around the site of Koh Ker while hunting game.

George Cœdès concluded from inscriptions that Koh Ker was capital of the Khmer empire (928 – 944 AD) under the reign of Jayavarman IV and his follower Harshavarman II.

After an interruption because of the reign of terror of the Khmer rouge, research at Koh Ker continued by APSARA, French, Japanese and Australian scientists.

[1]: 13 At the beginning of the 21st century, scientists concluded that not all of the monuments could have been built in the short time when Koh Ker was capital of the Khmer empire (928 – 944 AD).

[1]: 13–14 Excavations in December 2015 by Cambodian and international teams near Prasat Thom and the Rahal in the ancient urban core area of Koh Ker have yielded radiocarbon dates that clearly place significant habitation and activity beginning as early as the 7th-8th centuries CE - often noted as the Chenla period by historians.

Other exotic pottery include Thai and Vietnamese stoneware that generally date to the late Angkor and post-Angkor periods.

Natural and human resource management variables as well as environmental phenomena may have also played significant roles related to changes in popularity, population and productivity.

[citation needed] In late 2011, the remote location drew media attention worldwide when Sotheby's attempted to sell a statue of a mythical Khmer Empire warrior.

In March 2012, the US and Cambodian governments filed court documents[7] to seize the statue that they purport was illegally removed from the site.

A twin statue, also linked to the Koh Ker site, is on display at the Norton Simon Museum in Pasadena, California.

[citation needed] Before Koh Ker became capital of the Khmer empire (928 AD), numerous sanctuaries with Shiva-lingas existed already.

As later kings (whose residence was not in Koh Ker) changed from Hinduism to Buddhism they gave orders to make the necessary adjustments at their temples.

[citation needed] Several inscriptions were found which mention Koh Ker as capital of the empire in Siem Reap, Battambang, Takeo and Kampong Cham (city).

The inscriptions explain how manpower was organised: taxes in form of rice were raised in the whole country and served to provide for the workers who came from different provinces.

An inscription at Prasat Damrei says that the shrine on the top of the state temple (Prang) houses a lingam of about 4.5 m (14 ft 9 in) and that the erection of this Shiva-symbol gave a lot of problems".

A Sanskrit inscription at Prasat Thom gives evidence of the consecration of a Shiva-lingam 921 AD which was worshipped under the name of Tribhuvaneshvara ("Lord of the Threefold World").

Laterite and sandstone of excellent quality were quarried in great quantities in the region of Koh Ker, so the transport of the stones to the site was no problem.

[1]: 16–17 The huge Baray (water-tank) called Rahal is the largest object at the site of the ancient capital Koh Ker.

The original stairs are in a very bad condition as is the bamboo-ladder which was constructed in the 20th century, so it is forbidden to climb to the top of the pyramid via this route.

Two artefacts of the Prasat Pram can be seen in the National Museum in Phnom Penh: A damaged lion statue and fragments of a standing four-armed Vishnu.

[10] Another legend about the temple says that many years ago a powerful king Preah Bat Sorya Teyong lived at the Chiso mountain.

The statue of the two fighting monkey kings Sugriva and Valin (figures of the Hindu epic Ramayana) was found at this site and is now in the National Museum in Phnom Penh.

In each of the four corners stood a beautiful chiselled Garudu with raised arms giving the impression these mythical figures would bear the yoni.

The modern name Sralau refers to a species of tree[13] [1]: 25 Sometimes written Prasat Kra Chap, today the site has well preserved entrance gate and the ruins of 5 towers arranged in a quincunx.

A Sanskrit inscription found at the temple offers evidence that an erstwhile lingam was once erected on the top of the pyramid (Prang).