Mau Son Peak

The road that turns off National Highway 4B and climbs to Mẫu Sơn is only about 15 kilometers long. But every kilometer of it takes you one step higher, and the thermometer drops another notch.

Once the car reaches mountain road 237A, the change begins. The air grows cooler, pine forest appears on both sides of the road, and mist starts to drift around the bends. Mẫu Sơn is not a single mountain. It is a cluster of more than 80 peaks, large and small. It spreads across three communes of Lạng Sơn province. One shares the mountain's name. The other two are Công Sơn and Ba Sơn. The highest summit is Phja Pò, a local name that means Father Mountain. It rises 1,541 meters above sea level.

Mẫu Sơn is known as the coldest place in Vietnam. In winter, the temperature can fall to between minus 2 and minus 5 degrees Celsius. Snow and ice that turn the mountain forest white are real here. They come in the hardest cold spells. The mountain is so unusually cold because of the shape of the land. Its many ranges curve like bows that open to the north. Like a funnel, they catch the full force of the northeast monsoon pouring in from China. The air is often at 100 percent humidity. On the summit, the wind can reach force five or six, with gusts up to force ten.

Winter is only half of it. In summer, Mẫu Sơn is cool in a way few places are. Temperatures on the summit range from 16 to 21 degrees. The plains below are far hotter. That is why, early in the 20th century, the French took notice of Mẫu Sơn and decided to make it a retreat. They built a road up the mountain. In the 1920s and 1930s, they put up about 40 buildings of cut stone in a Western style, meant for officials and the upper class. In those days the mountain ranked alongside Da Lat, Sa Pa, Tam Đảo and Bà Nà among the French resorts of Indochina.

Today most of those villas stand abandoned, their walls covered in moss, but they still hold firm. The Nine-Room Villa is the most intact of them all. Before those mossy walls of blue-gray stone, it is easy to picture French officials a century ago, sitting on the verandas and watching the clouds roll over the peak. They might have felt they were in some corner of Europe, in the heart of Indochina.

Mẫu Sơn is also a land where the Tày, the Nùng, the Dao and the Kinh live side by side. The Tày and the Nùng are two peoples of northern Vietnam with closely related languages and similar cultures. The Kinh are the majority ethnic group of Vietnam. Mẫu Sơn commune alone has 19 villages. The Dao make up more than 15 percent of its people. They live mostly in the high villages. They hold the know-how for distilling rice liquor with leaf yeast.

Mẫu Sơn liquor is distilled from rice with a leaf yeast. The yeast is mixed from more than 30 kinds of forest herbs. The Dao ferment it in sealed jars and crocks for many days before they distill it. In 2024, Lạng Sơn province gave the liquor a four-star OCOP rating. OCOP, short for One Commune One Product, is a national program that rates local products with stars.

On slopes wrapped in mist all year round, above 700 meters, about 3,000 Shan tuyết tea trees grow wild. They grow across the same three communes. After a survey in April 2026, 111 of them were recognized as heritage trees. They are between 100 and 300 years old. These old tea trees, growing in the mist generation after generation, are the living natural heritage of these mountains.

Just as remarkable are the rhododendron forests. At about 1,000 meters, late in the spring, white and red rhododendrons burst into bloom on the slopes. They flower about a month later here than on the high mountains of the Northwest, at their peak in the second half of April. In the drifting mist, their clusters glow like small flames on the mountainside.

On June 28, 2025, UNESCO officially recognized the Lạng Sơn UNESCO Global Geopark. It is the fourth global geopark in Vietnam. Mẫu Sơn lies within it, in a landscape shaped over 500 million years of the Earth's history.

On the summit of Phja Pò, clouds roll across rows of hundred-year-old heritage tea trees, and blazing red rhododendrons bend under the mountain wind. It is easy to see why the French climbed up here a century ago and did not want to come down. Then the road winds back down the pass, and with every kilometer the air grows a little warmer.