កាលបុរសនេះនៅដឹកនាំ គ្រានោះកម្ពុជាមានឈ្មោះថា ចក្រភពខ្មែរ ព្រំដែននៅជាប់នឹងប្រទេសចិន (ហើយហួសទៅឯជើងទីក្រុងហាណូយទៅទៀត), ប្រទេសសៀមឥតទាន់មានទេ,​ ប្រទេសលាវឥតទាន់មានទេ, ព្រំដែនខាងលិចជាប់នឹងប្រទេសភូមា ឬមីយ៉ាន់ម៉ាសព្វថ្ងៃ និងសមុទ្ធអានដាមែន (Andaman Sea) , ព្រំដែនទិសនីរតី (ទិសខាងត្បូងឆៀងខាងលិច) ជាប់នឹងប្រទេសម៉ាឡេស៊ី, ព្រំដែនទិសអាគ្នេយ៍ (ទិសខាងត្បូងឆៀងខាងកើត) ជាប់នឹងសមុទ្ទចិនខាងត្បូង។
When this statesman led, that time Kampuchea (Cambodia) known as the Khmer Empire, and look at the map, where Cambodia’s borders are; no Siam (Thailand) and Laos.

Jayavarman VII (Khmer: ជ័យវរ្ម័នទី៧), known posthumously as Mahaparamasaugata (មហាបរមសៅគាត, c. 1122–1218), was king of the Khmer Empire. He was the son of King Dharanindravarman II (r. 1150–1160) and Queen Sri Jayarajacudamani. [2] He was the first king devoted to Buddhism, as only one prior Khmer king had been a Buddhist. He then built the Bayon as a monument to Buddhism. Jayavarman VII is generally considered the most powerful of the Khmer monarchs by historians.[3] His government built many projects including hospitals, highways, rest houses, and temples. With Buddhism as his motivation, King Jayavarman VII is credited with introducing a welfare state that served the physical and spiritual needs of the Khmer people. Source wikipedia

Map source – Wikipedia

Jayavarman VII (Khmer: ជ័យវរ្ម័នទី៧), known posthumously as Mahaparamasaugata (មហាបរមសៅគាត, c. 1122–1218), was king of the Khmer Empire. He was the son of King Dharanindravarman II (r. 1150–1160) and Queen Sri Jayarajacudamani. He was the first king devoted to Buddhism, as only one prior Khmer king had been a Buddhist. He then built the Bayon as a monument to Buddhism. Jayavarman VII is generally considered the most powerful of the Khmer monarchs by historians. His government built many projects including hospitals, highways, rest houses, and temples. With Buddhism as his motivation, King Jayavarman VII is credited with introducing a welfare state that served the physical and spiritual needs of the Khmer people.

The Khmer Empire was a Hindu-Buddhist empire in Southeast Asia, centered around hydraulic cities in what is now northern Cambodia. Known as Kambuja (Old Khmer: កម្វុជ, romanized: Kâmpŭchéa) by its inhabitants, it grew out of the former civilisation of Chenla and lasted from 802 to 1431. Historians call this period of Cambodian history the Angkor period, after the empire’s most well-known capital, Angkor. The Khmer Empire ruled or vassalised most of mainland Southeast Asia and stretched as far north as southern China. At its peak, the Empire was larger than the Byzantine Empire, which existed around the same time.

The beginning of the Khmer Empire is conventionally dated to 802, when Khmer prince Jayavarman II declared himself chakravartin (lit. ’universal ruler’, a title equivalent to ’emperor’) in the Phnom Kulen mountains. Although the end of the Khmer Empire has traditionally been marked with the Fall of Angkor to the Siamese Ayutthaya Kingdom in 1431, the reasons for the empire’s collapse are still debated amongst scholars. Researchers have determined that a period of strong monsoon rains was followed by a severe drought in the region, which caused damage to the empire’s hydraulic infrastructure. Variability between droughts and flooding was also a problem, which may have caused residents to migrate southward and away from the empire’s major cities.

The site of Angkor is perhaps the empire’s most notable legacy, as it was the capital during the empire’s zenith. The majestic monuments of Angkor, such as Angkor Wat and the Bayon, bear testimony to the Khmer Empire’s immense power and wealth, impressive art and culture, architectural technique, aesthetic achievements, and variety of belief systems that it patronised over time. Satellite imaging has revealed that Angkor, during its peak in the 11th to the 13th centuries, was the most extensive pre-industrial urban complex in the world.[9][10] Researchers have also concluded that the Khmer Empire invented the world’s first healthcare system, which included 102 hospitals.