In the steep gorge of the Longchuan River, a single salt-producing town once generated over sixty percent of Yunnan’s entire salt tax. This wealth began with a lost beast. Local memory credits a Yi woman named Li Achao, who followed her unusually fat black cow into the valley and watched it lick the salty earth. By the Han Dynasty, locals were boiling this brine. In the Ming Dynasty, the state relocated sixty-four skilled salt-making families from Yingtian Prefecture to scale up production. These families, alongside local Yi farmers who carved rain-fed terraces into the northern slopes, transformed the valley. Caravan horses left deep, polished hoofprints in the red sandstone paths, carrying salt across the Southwest Silk Road.

The town's architecture adapted to the tight geography. Builders used local red sandstone and timber to construct "four courtyards with five skywells" and "walkhorse corner towers." To protect this wealth from mountain torrents, workers built the Qing'an Dike, a massive red sandstone barrier bound together by a mortar of sticky rice, lime, bean milk, and clay. Nearby, the grand Wu Family Mansion rose with ninety-nine rooms and one hundred and eight doors. Its owner, Wu Weiyang, became the first merchant in Yunnan to import a private automobile. At the Great Dragon Temple, a wooden plaque carved with nine dragons bears the brushwork of the Yongzheng Emperor, praising the salt springs as a universal blessing.

Today, the roar of the Chengdu-Kunming Railway cuts through the northern valley, running parallel to the ancient terraced fields. Local farmers still plant crops on these steep contours. Visitors walk the narrow streets to taste traditional gray tofu, which is fried until golden and then soaked in alkaline water to turn the interior back into smooth soy milk.

The boiling fires have cooled. The red sandstone streets and the green steps of the northern terraces remain, preserving the quiet intersection of ancient industry and mountain agriculture.