Pha Din Pass has a length of about 32 km on National Highway 6, is the junction between Son La Province and Dien Bien Province. Pha Din is one of the "Tu Đai Dinh Deo" in the Northwest, together with O Quy Ho Pass, Khau Pha Pass, Ma Pi Leng Pass. "Pha Din" in Thai language means "heaven and earth", this is the junction between heaven and earth. According to the legend here, in order to resolve disputes, Lai Chau and Son La provinces had to organize a horse race for demarcation. Up to the top of the pass, you'll feel the majestic natural beauty, interspersed valleys, villages which together created a colorful picture.