This paper sets out to explore the potential of “3S” (GIS, RS and GPS) technology in the area of historical geography studies in particular. During the later years of Tang dynasty the most of lands between Yellow River and Yangtze River suffered a chaotic juxtaposition of separatist regimes, i.e., FangZhen. By using relevant vector data, GPS data and remote sensing satellite imaginary on the appropriate platform of GIS, we improved the quality and accuracy of scientific studies of FangZhen Period much more than before. Tang FangZhen Information System, a focused custom GIS system, has also been developed here to explore the formation and development of FangZhen. GIS processes such as area, point and line representation and tracing, image/feature/script hotlinking and thematic representation are perfect to trace and display historical data across space.