The Yan State's Eastward Territorial Expansion during the Eastern Zhou Dynasty

It is clear that the Yan state enlarged its territory beyond the Yanshan Mountains from the 6th to 3rd centuries BC, based on the chronology of ritual bronze vessels, bronze weapons and burial pottery of the Yan state accompanied with the Liaoning-type daggers and Liaoxi-type halberds of Northern bronzes, as indicated by the analysis of graves in the graveyards of Dongdazhangzi, Jianchang Prefecture, Liaoning Province. This research clarified the processes behind the distribution of Yan artifacts and tombs which emerged in areas originally populated by people associated with Northern bronzes. This process firstly suggests that they spread to the Luanhe River Valley of the Yanshan Mountains during the 6th and 5th centuries BC. Then, during the time of administration of the Yan Wengong (Yan Chenghou), the territory of the Yan state enlarged to encompass the Liaoxi district during the 4th century BC. In addition, this research discovered archaeological evidence for historical documents showing that King Zhaowang founded five administrative offices, such as the Shanggu administration, and that the territory of the Yan state expanded in the Liaodong district from the end of the 4th century to the beginning of the 3rd century BC. The eastward expansion of territory indicated the development of the Yan state, which was one of the Warring States behind agricultural society. The expansion of territory also shows the dawning of a new era, in that the increase of agricultural products grown using decarbonized cast iron tools triggered the expansion of agricultural land. This new economic evolution, which brought about the end of a clan-based society, resulted in a new class of urban citizens the likes of which had hitherto been unknown, including new farmer and merchant classes. This development accords with the movement of the Yan state as one of the Warring States in the manner in which it expanded its territory to seek out new land for fields among the lands of the Northern bronze people. The Yan state's eastward expansion of territory as indicated by archaeological evidence suggests that it indirectly administrated the Liaoxi district during the 6th and 5th centuries BC, that it occupied the whole of the Liaoxi district by the 4th century BC, and that it founded administrative offices reaching to the Liaodong district during the 3rdcentury BC. This eastward enlargement of territory by the Yan state indicates not only the extension of the territory of Liaoxi and Liaodong districts but also a cultural movement triggering a new culture on the Korean Peninsula. It also indicates the establishment of the Chondode pottery culture and the slender bronze dagger culture of the Korean Peninsula. As part of this process, iron tools andiron production techniques spread to the Korean Peninsula and then on to the Japanese Archipelago