The relevance of this study is conditioned by the dynamic development of the guzheng zither of medieval and folk instruments of Inner Mongolia, Manchuria (North and North-East China), Mongolia, the Far East and Southern Siberia (Russian Federation), the original prototype of which is one of the oldest string plucked instruments in China – the se zither (瑟). The purpose of the study was to investigate the design features and tuning methods of se zither (瑟). A system of scientific research methods was used, namely organological analysis, comparison, deduction, and abstraction. As a result of the study, it was found that the se zither (瑟) differs from the classical Chinese zither qín (琴). Given the study of historical and archaeological sources of the 7th – 2nd centuries BCE, the oldest area of distribution of the xie zither was found within the ancient kingdom of Chu (6th – early 2nd century BCE), whose population was ethnically different from the Huaxia Chinese, and its modification, the zheng zither (箏), during the Qin dynasty (771 – 221 BCE). In addition, the ways of its infiltration into the medieval instrumentation of the ancient peoples of these regions of Central and South-East Asia were determined. The shape, design features, and the method of tuning with movable stands have established the genetic connection of this type of zither with ancient and traditional instruments of Turkic and Mongolian ethnic groups and its infiltration into the medieval court instruments of the Tunguska-Manchu.