There is a legend in Suzhou: In ancient times, when Houyi shot the sun, a sun stone splashed down on the seashore, and later generations built a city here, which was a famous Yangcheng. One day, the rainstorm poured down and Yangcheng sank, so it was called "Yangcheng Lake".
from the perspective of geological structure, Yangcheng Lake is located between the Hu (Zhou) Su (Zhou) fault zone and the Su (Zhou) Kun (Shan) Jia (Ding) fault zone, and the two fault structures generally control and form the scope and outline of Yangcheng Lake today.
From the ancient books before the Song Dynasty, no records about Yangcheng Lake have been found so far. Later generations found dense ancient cultural sites in Taihu Plain around Yangcheng Lake. Yuan He Wei Ting Zhi contains: "In the 17th year of Wanli (Ming Dynasty) (1598), Yangcheng Lake dried up, and a bamboo coffin was trapped in the lake." It is also said that there is a stone tablet, two feet long, and the words are indelible, which is still at the bottom of the lake. " The same book also contains: "(Qing) In the first year of Yongzheng (1723), there was a great drought, and Yangcheng Lake dried up. From the road to the shore of Chilu, there were thousands of wells, and farmers brought hoes with them, and many porcelain bowls were obtained. It is said that Song Hanzhong offered his father a taste of training here, and the sergeant brought wine with him, and there was something in the iron ware containing silver and copper." It can be seen that the main body of Yangcheng Lake should be formed in the post-Song period.
during the Tang and song dynasties, the climate turned warm and humid, the temperature and precipitation were higher than before, the sea level rose, and the tide was increasingly serious. The Song Dynasty's "Wu Junzhi" recorded: "Although Kunshan passed through mountains and seas, there was no tide since ancient times. Shaoxing middle school. The tide began to reach the county. In the end, the tide suddenly came and drove past Yiting (now Weiting Town). " The above situation caused the river to be silted up, and the river was not vented smoothly, so the river on the depression of Yangcheng Lake expanded and evolved into a lake, and finally it was integrated to form Yangcheng Lake.
In February, 194, Yangcheng Lake established an anti-Japanese democratic government, which was called Yangcheng County Government. It was recorded in writing, which is the earliest origin of the place name "Yangcheng" seen so far.