The West became aware of Angkor through the published diaries and drawings of Henri Mouhot, a French naturalist who visited Angkor in 1860. France acquired administrative jurisdiction over Cambodia in 1863. After surveying Angkor to determine its extent and layout, the French worked for nearly 75 years, starting in the beginning of the 20th century, to preserve the monuments. In 1972 French archaeologists were forced to leave Cambodia during the upheaval caused by civil war. Damage to Angkor's monuments during the Khmer Rouge (Cambodian Communist movement) regime of 1975 to 1979 was minimal.
In the 1970s most of Angkor's monuments began to suffer from neglect and looting. An enormous amount of Khmer art was transported across the border into Thailand and then sold on the international market. In the mid-1980s an international appeal for assistance in preserving Angkor inspired organizations from India and Poland to undertake preservation work on Angkor Wat and the Bayon. Offers for assistance increased following the end of the civil war in Cambodia in 1991. In recent years, international foundations and countries, including France, Japan, and Germany, have been helping the Cambodian government conserve sites. Advanced research techniques such as aerial photography, a geographic information system (computer system that records and analyzes geographic data), and satellite-based radar imaging enable archaeologists to construct maps of the ancient city and to detect ruins in inaccessible areas of the jungle.
