In 1045BC, King Wu of the Zhou Dynasty exterminated the Shang Dynasty and enfeoffed northYan (where Beijing is now located) to Duke Zhao, a noble who shared the same family name with himself. The Hereditary House of Duke of Zhao of Yan from the Historical Records by Sima Qian recorded the historical fact. Duke of Zhao, called "Jun" in the literary literature, was appointed as Grand Guardian, who was one of the Three Dukes. It was he who had the layout of the city of LuoYang programmed and helped King Cheng of the Zhou Dynasty out of the turmoil caused by the rebellions of Wugeng and Lufu, sons of King Zhou of the Shang Dynasty. The rebellions happened in the districts which were originally princedoms of the late Shang Dynasty, including Dongyi, Xu, Yaan and Bogu,etc. He stroke while the iron was hot and pursued enemy troops in retreat northward and in this way consolidated the rule of Zhou in the north and the east. It was probably in this period that Yan, the proper place, was enfeoffed to Duke Zhao to better safeguard the peace and development of the border lands of the Western Zhou Dynasty. However, Duke of Zhao had to remain in the royal court offering assistance and his eldest son, Ke, went to Yan to rule in stead of his father. Ke, as a matter of fact, is the first marquis of Yan. He was also bestowed six tribes. Hence, he set up official organizations concerned in the district of Yan, to exercise rule over the land and the people there. The bronze ware "Ke" and Ke's inscriptions, which were unearthed from the No. 1193 main tomb in the Huangtupo site of Liulihe County, recorded the lost historical fact mentioned above.

At the initiation of the Yan State, the ruler established the capital of Yan of the West Zhou period in the place where a village named Dongjialin situates now, exactly speaking, in the east of Liulihe town of Fangshan district. This city has been discovered as the earliest city location in the Beijing area and it has a history of over three thousand years. The city was built on a hathpace northeast to the Dashi River and the archeologists have a general understanding of this ancient city location after the twenty-year archeological drilling and exhumation. The footing was 829 meters long from east to west and over 700 meters wide from north to south, and the wall toft was tamped in different layers on the crudely flat ground. The wall toft had a width of about 8 meters and was made up of 3 layers, with the width of each layer ranging from 2 to 7 meters. Within the wall, protection slopes were built. The tamper-socket has the diameter varying in the range of 3 to 5 centimeters. In the northeast corner of the east city wall was found a drain made of screes which must be the pipeline carrying water from the inside to the outside of the city. Lying outside ten meters away from the city-wall outboard was a moat, with a 15-meter outfall. Outside the southern city wall and the southern sections of both the east and the west city wall, the moat became a piece of beach as the result of the scouring by the Dashi River and the riverway could not be identified clearly.