Sukhothai Kingdom
The Sukhothai Kingdom broke free from the Angkor Empire around the 13th century. Although Isan is not thought to have been a part of the Sukhothai kingdom due to the lack of clear evidence, the Khmer empire became weaker and retreated to its Cambodian heartlands, leaving Isan in the hands of fragmented "muang" () "city-states" or statelets. However, many Khmer-speaking people remained and are still a prominent fixture in the southern area, constituting the majority in present-day southern part of the region such as in present-day Surin Province, Buriram Province and are also numerous in part of Sisaket Province.