There have been records of artificial excavations in Wu Kai in the Heavenly Palace, which was first published in 1637 (Ding Chou in the tenth year of Chongzhen in Ming Dynasty), with 18 articles in three volumes. The book covers agriculture and handicrafts, such as machinery, bricks and tiles, ceramics, sulfur, candles, paper, weapons, gunpowder, textiles, printing and dyeing, and salt making.

Salt wells have a long history. Long before the Tibetan Tubo Dynasty, Tibetan tribes had salt fields on their own side. It is said that Mangkang Port is famous for producing salt in the six mountains of Duokang. The legendary battle between King Gelsall and Qiang Ba, the king of Naxi nationality, for salt in the salt well is called "Qiang Ling Battle".

In the end, King Gelsall defeated Qiangba, occupied the salt well, and captured Yula, the son of Naxi king. In the late Tubo Dynasty in Tibet, Prince Yula of Naxi became the minister of Naxi in King Gelsall, and Yantian was given to Prince Yula of Naxi. The oldest and most primitive salt-making method has been preserved to this day.

Because the fold belt and big fault formed in the process of crustal rise in Yanjing area happen to be salt-bearing strata, the hot springs flowing out of the fault zone dissolve the salt-bearing strata, and the brine rich in salt is continuously ejected, forming large and small salt wells.

Extended data:

The full name of Millennium Yanjing is "Yanjing Naxi Township, Mangkang County, Xizang Autonomous Region", which is located on the Yunnan-Tibet line between Mangkang County and Deqin County on the east bank of Lancang River in Hengduan Mountain area, bordering Jinsha River in the east and Lancang River in the west, with an average elevation of about 2,400 meters. It is 5 km away from Mangkang County1/kloc-0 in Tibet and 0/00 km away from Deqin County/kloc-0 in Yunnan.

Yanjing is a magical place in Tibet. Historically, it is the main road from Tubo to Nanzhao, and it is also the only way for Yunnan tea to be transported to Tibet. The humanistic landscape of Yanjing Yantian is the only remaining artificial original salt-drying landscape on the "Tea-Horse Ancient Road".

Every spring, the best brine comes from Lancang River. At this time, when you come to Yanjing, you can see women working and drying salt in Yantian. At this time, it is the season when peach blossoms on both sides of the Lancang River open one after another, and the salt produced is of good quality, which is called "peach blossom salt".

There are rich brine resources along the Lancang River, and there are dozens of steaming natural salt wells. Every spring, the best brine appears along the Lancang River. Underground brine is extracted by drilling wells (naturally formed or produced after salt ore injection), and the salt made is called well salt, and the shaft for producing well salt is a salt well.

Baidu encyclopedia-Yanjing town

Baidu Encyclopedia-Tiangong Wu Kai