According to legend, Xu Fu once wrote a letter saying that there are three fairy mountains in the sea: Penglai, Fangzhang and Yingzhou, where gods live. So Qin Shihuang sent him to lead thousands of boys and girls as well as three years of food, clothing, medicine and farming tools that had been prepared to go into the sea to seek immortality, which cost a lot of money.

However, Xu Fu led his troops to sea for several years and failed to find the sacred mountain. Xu Fu also left his descendants in the local "Laoshan", and their descendants changed their surnames to Lao or Lao.

In 210 BC, the First Emperor of Qin visited Langya on his eastward tour. Xu Fu excused himself by saying that he encountered a giant shark after going out to sea and was unable to sail far, so he asked for more archers to deal with the shark.

Qin Shihuang agreed and sent archers to kill a big fish. Later, Xu Fu led his people to the sea again and came to "Plain Guangze". He felt that the local climate was warm, the scenery was beautiful, and the people were friendly, so he stopped and proclaimed himself king, teaching the locals how to farm, fish, whaling, and paper-leaching. He never returned to Qin again.