Why did the Qing Dynasty move the residents of the seaside?

In the 18th year of Shunzhi in Qing Dynasty (166 1), in order to stop the centrifugal force at sea, the imperial court decided to relocate the coastal residents. 30 miles from the coastline, build a wall, set fire to the houses outside the boundary, and drive the residents out of the boundary. Those who dare to cross the boundary will be killed.

The national policy of moving to the sea was appalling and lasted for more than twenty years.

Under the command of moving to the sea, the jade island along the southeast coast of Zhejiang Province instantly turned into ruins, with dense hazel trees. After the establishment of Yuhuantang in the sixth year of Yongzheng (1728), the government gradually attracted immigrants from all over the country to reclaim land and redevelop Yudao.

There is a man named Zheng Shibao in Ruian County, Wenzhou. He was one of thousands of people who left their homes in those years. He responded to the call, came to the island and settled in a place called "Chaodongwu Natural Village, Huxin Village, Waitang Township, Chumen Town, Yuhuan County". Perhaps he didn't expect that a century later, the village was nine times out of ten a descendant of Zheng.

Shi is my ancestor, namely "Gong Zu". Gong Zu got married here and gave birth to six sons. Each of the six major schools has its own reproduction.