Conquer the challenge of exploring Phja Da, the highest mountain in Cao Bang province The majestic Phja Da mountain is nearly 2,000 m above sea level, one side belongs to Son Lap commune (Bao Lac) and the other side belongs to Thai Son commune (Bao Lam). In spring and winter, white clouds are like soft silk strips layer by layer covering the mountains. In the summer it rains a lot, the mountain tops are like giant waterfalls pouring down from the sky. In autumn there are few clouds, the sun shines brightly on Phja Da mountain like a giant fire tower soaring into the sky. At the foot of Phja Da mountain is the source of the Nang River, where the Mong and Dao people live, cultivating terraced fields on rocks, creating winding golden ribbons on the back of the mountain.