After the establishment of Yue State in the late Spring and Autumn Period, its land began to belong.
In the 25th year of Ying Zheng, King of Qin (the first 222 years), Huiji County was established and Zhangxian County was located. Because the local area is located in the east of Juzhang County, it was called Juzhang Cave Well in 843.
Tang Wude four years (62 1), ancient sentence analysis, divided into Yao and Yin States. In eight years, Yinzhou was changed to Jixian County, and the local name was changed to Tokyo County. In the fourth year of Tang Yuanhe (809), Wanghai Town was built at the mouth of Yongjiang River in eastern Hebei, which was the beginning of Zhenhai's governance of the town.
In May of the third year of Kaiping in Hou Liang (909), King Qian Liu of wuyue visited Mingzhou and built a city in Wanghai Town. In leap August, Wanghai County was set up in Qian Liu (Taiping Yuhuan), which was the beginning of establishing the county, because Wanghai Town had the advantage of fishing and salt. It was soon changed to Dinghai County. At that time, the county only governed Qingquan, Xu Ling, Chongqiu and Jintang.
In the tenth year of Song Xining (1077), Lingyan, Taiqiu and Haiyan in Yin County were designated as Dinghai, and in the first year of Yuanfeng (1078), Jintang was designated as Li Chang, and Qingquan was divided into two townships. Since then, the county has governed seven townships and has been designated as Shang County.
The system of attacking Song Dynasty was established in Yuan Dynasty. Ming Hongwu twenty years (1387), abandoned the county and changed to Wei. The original Guo Chang County (now Zhoushan City) was placed under Dinghai County until the reign of Kangxi in the Qing Dynasty.
In the 26th year of Kangxi (1687), Dinghai County was changed to Zhenhai County, and Dinghai was established in 778. The following year, Dinghai County built the original border. So far, Zhoushan has belonged to Zhenhai for 300 years. The establishment of Zhenhai County remained unchanged during the Republic of China.
After the founding of People's Republic of China (PRC), due to political and economic construction and other factors, the organization changed and the county boundaries changed frequently. At the end of 1954, the town north of Longshan 10 was placed under Cixi County (now Cixi City); Five townships in Cidong, such as Hetou and Changshi, belong to Zhenhai; Tanghu Island at the mouth of Hangzhou Bay belongs to Shengsi. 1958 Entering Wenxi Township from Yuyao County; At the end of the same year, the county was withdrawn and merged into the city, and Zhenhai County was restored in 1963 and 65438+ 10. 1July, 985, it was merged into Ningbo again. In June of the same year 10, the county organizational system was officially abolished and zhenhai district was established. The name of Zhenhai County lasted for 299 years. The period from the founding of the county to its revocation is 1077.