The Cambodia–Thailand boundary was established through agreements between France, which ruled Cambodia from 1863 to 1953, and Siam (modern-day Thailand) in 1904 and 1907. The boundary extends for approximately 885 kilometers (550 miles) from the Gulf of  Thailand to the tripoint with Laos, following watershed lines for about two-thirds of its length. There has been some demarcation of the southern section of the boundary, but the precise alignment of the border in the Dangrek Mountains has yet to be agreed upon due to discrepancies in the depiction of the watershed on the 1907 French map with the reality on the ground.

Determining sovereignty over the Temple of Preah Vihear has been particularly contentious for modern-day Cambodia and Thailand. In 1962, the International Court of Justice ruled in favor of Cambodia’s claim to the Temple based on the importance of the 1907 Dangrek map. A subsequent ruling by the ICJ in 2013 clarified that Cambodia has sovereignty over the vicinity of the Temple, but further negotiations will be needed to precisely locate the boundary on the ground and completely resolve the dispute.