Kingdom of Champasak
After the Khmer Empire began to decline in the 13th century, Isan was dominated by the Lao kingdom of Lan Xang, which had been established by Fa Ngum. Due to a scarcity of information from the periods known as the dark ages of Cambodia, the plateau seems to have been largely depopulated. There were few if any lines of demarcation, for prior to the 19th century introduction of modern mapping, the region fell under what 20th century scholars called the "mandala system". Accordingly, in 1718 the first Lao mueang in the Chi River valley — and indeed anywhere in the interior of the Khorat Plateau — was founded at Suwannaphum District (in present-day Roi Et Province) by an official in the service of King Nokasad of the Kingdom of Champasak.