Archaeological data from Eastern Thailand, along the border between Thailand and Cambodia suggests occupation from at least 4000 BP until the beginning of State formation around the 6th century CE, and beyond. The appearance of Pre-Angkor in Cambodia and Dvaravati in Thailand around the early 7th century CE is based on inscriptions found in both areas. The various archaeological evidence discovered, predominantly in Eastern Thailand, indicate the cultural diversity among the main power kingdoms in the region, including Zhenla and Dvaravati. The data can be used to imply the political influences of those that governed the region. This paper aims to identify the settlement pattern of the Boundary States and their networks in Eastern Thailand, along the ancient frontier between Dvaravati and Pre-Angkor States around c. 600-800 CE. The study is approached through Core-periphery and Central Place theory to aid in the reconstruction of the ancient networks between the States of Zhenla and Dvaravati. Using GIS software to calculate site size and distance between settlements indicates a site-hierarchy that can be classified into 3 rankings: Central Town, Sub Town, and Village. The least-cost pathway analysis suggests transport routes based on location and distance between sites. The results suggest that 4 Central Towns were the “urban centers” in this frontier region. The Boundary State is considered a central place or gateway based on site density and complexity of monuments. Significantly, the inscriptions, sculptures and built environment found in the study area are likely to be characteristic of both cultures, and this implies a political territory located between Dvaravati and Zhenla kingdoms existed in Eastern Thailand.