To reach Dien Bien province from Hanoi, travelers have to pass Pha Din pass that is about 32 km long. In the local language, Pha Din means heaven and earth. According to a local legend, Pha Din Pass is the place where the sky meets the earth, so it is considered as the frontier between Heaven and Earth. Long time ago, there existed a deputation on the border between Lai Chau and Son La provinces. It was solved by a horse-racing. Two horses started from each side of the pass and the border was determined at the point where they met each other. The horse of Lai Chau province ran faster than the one of Son La province so the pass belonging to Lai Chau is longer than that of Son La.

At the height of above 1,000m, the pass is full of twists and turns, one side is an upright cliff and the other is a deep gulf. So, climbing and descending the slopes with their many bends and deep gorges, amid such magnificent scenery, is an unforgettable trip in Vietnam.