High atop the Dangrek Mountain chain sits the ancient and sacred Temple of Preah Vihear, a site whose stones are steeped not only in history but in geopolitical conflict between Cambodia and Thailand. Though the site is a deep-rooted pilgrimage location central to the national identity of both nations, its rightful ownership was brought before the International Court of Justice with the original case filing on 6 October 1959.

The dispute revolves around two documents from the early 20th century: the Franco–Siamese Treaty of 1904 and its accompanying Annex I Map. The 1904 Treaty had established that the boundary should follow the natural watershed line. However, the Annex I Map, drafted by French surveyors, placed the temple within Cambodian territory, despite it being located on the Thai-facing side of the ridge and physically accessible only from the north.

For Cambodia, this map, subsequently approved by the Mixed Commission of 1907, is the definitive proof of sovereignty. Cambodia contends that during the proposal of the map, Thailand maintained an extended silence which was interpreted as having no objections. This silence, Cambodia argues, constitutes the legal principle of estoppel, allowing the commission to proceed after the statute of limitations for objections had passed and leading to the assumption that the land remained under Cambodia’s control. Cambodia, having since gained independence from the French, now seeks the removal of all Thai forces and military presence from the area.

Thailand, however, fiercely objects to the map’s validity. They argue that the French-drafted Annex I Map was not jointly prepared or officially approved by Thailand, and that its government did not fully understand that accepting the map would result in the loss of territory. Crucially, Thailand maintains that a map cannot override the terms of a treaty, asserting that the map incorrectly drew the watershed line required by the 1904 Treaty and failed to notify Thailand of this deviation. Furthermore, Thailand rejects the principle of estoppel, arguing that its lack of response was due to a lack of awareness of the map’s inaccuracies, and therefore, this silence should not be interpreted as agreement. To support its claim to the site, which holds long-standing cultural and religious significance for the Thai people, Thailand has submitted documents showing administrative control through 1930, including patrol records, tax collection and policing records.

The tension culminates in the case presented before the court. The Justices have the difficult task of navigating complex international treaties and determining within whose territory this sacred site lies.