The exact location of this 254km-long ancient route has been identified for the first time by the Living Angkor Road Project supported by Thailand Research Fund.
A collaboration between Thai and Cambodian researchers, the Thai team is led by remote-sensing expert Col Surat Lertlum while the Cambodian team is led by anthropologist Im Sokrithy.
The research started with the clues in the 12th-century Stone Inscription saying that King Jayavarman VII had ordered 17 rest houses built along the Angkor-Phimai royal road.
A study by French scholars a century ago identified most of the rest houses but did not identify the exact route.
By integrating advanced technology in remote sensing, geographical information system and geophysics with conventional studies in anthropology, archaeology and history, the Living Angkor Road Project has found the missing links.
In addition to the missing rest stops, the discovery of ancient bridges helps pinpoint the outline of the royal road as well as locating the connecting point on the Thai-Cambodia border at Chong Ta Muean in Surin province.
Moreover, they have found several ancient industrial sites and communities which could shed more light on the relationships of people along the route, and probably also the rise and fall of the ancient Khmer empire.
This research is yet more proof that we must step beyond our comfort zones to connect with other fields of expertise in order to raise our plane of knowledge.
When relations between Thai and Cambodia are often strained by ultranationalism and conflicts over ownership of archaeological sites, it is refreshing to see how the researchers' sheer dedication to knowledge can free them from nationalism, another form of egotism.
Equally refreshing is their respect for the local villagers' knowledge. Where the ancient sites are covered by forests or modern roads, the advanced technology of remote sensing can identify only the broad area, needing ground surveys, said Col Surat.
Without the local legends linking the ancient royal road and the villagers' knowledge of their areas, the research teams could not possibly have found the missing rest houses nor established the outline of the Angkor-Phimai ancient route, he added.
These villagers are struggling with harsh poverty, which is a world apart from the modern luxury in Siem Reap. Things are changing there.
At the Bayon Temple, however, the bas-reliefs depicting the lives of little people show us that for the peasants, their life has not changed much from 800 years ago.
As these villagers happily sang and danced their way to their temples to celebrate Asalaha Bucha and Buddhist Lent, I couldn't help wonder if this royal road project could give our countries more than tourism potential.
Though built by a great Buddhist king, the ancient rest houses have been changed to places of worships of different faiths over time. Now ruined, they best attest to the law of impermanence.
The multi-disciplinary approach and the researchers' no to ultranationalism is also in line with the Buddha's teachings on letting go of self to attain peace and truth.
Our world is rocked with violence from racist nationalism, environmental destruction from insatiable greed and political instability from ego clashes.
If archaeological ruins can remind us of the law of impermanence to reduce our greed and ego, they will best serve our present.
If so, we will not have to worry about the future.
Sanitsuda Ekachai is Assistant Editor of TheBangkok Post.