There is no city in the south of Kunshan, and the site is located in Beitan Village, bacheng town, Kunshan City, Jiangsu Province. Another nickname of Kunshan is Wucheng (or South Wucheng). Strictly speaking, Nanwu is another name for Xinyang (a part of Kunshan). There are many ancient books about Wucheng or Nanwucheng. "History of Han Dynasty Geography" Download from Lou County, Huiji County: "Lou has Nanwucheng, He Lu and others." "Qing Jiaqing Tongzhi" Suzhou House Download: "Nanwucheng is in the northwest of Kunshan County. Yue Jue Shu:' Lou County has a city, 30 miles away from the county, and now it is a township.' Gu:' there is wucheng village, which is guaranteed in zhutang township' ... "Brazil" also records:' wucheng is located in the west of town. "Now known as Wuchengtan Township, there are more than 100 villages." From 5 14 BC to 486 BC, Sun Wu carefully designed and built the Bagua Watertown according to Fu's "Bagua" map, using the principle of the change and evolution of Yin and Yang, and combining with the terrain and environment. Watertown is divided into central city, inner city and outer city, with a total of 12 waterway exits. After the completion of Nanwucheng, it effectively defended the threat of the Yue navy and the north to Wu. Nanwucheng is 3.5 kilometers wide from east to west and 4 kilometers long from north to south, covering an area of about 16 square kilometers, surrounded by Donggang, Yangcheng Lake, Xielu Port and Qilitang respectively.