The Heishui to Yakxia section of National Highway 347 enters a scenic spot soon after leaving Heishui County, Aba Tibetan and Qiang Autonomous Prefecture, Sichuan Province. The scenery along the way continues all the way to the Yakxia Snow Mountain, a total of about 40 kilometers, and the locals call it Naizigou. Because it is famous for the beauty of colorful forests, it is also called the "80-mile Colorful Forest Gallery". The reason why Naizigou is beautiful is first of all its rich tree species. Heishui County has a plateau monsoon climate, with sufficient sunshine and a large daily temperature difference, which has created rich ecological resources, extremely high forest coverage and numerous natural scenery in the territory.
The "80-mile" valley extends from an altitude of more than 2,000 meters to the Yakxia Snow Mountain at an altitude of more than 4,000 meters. The trees distributed on the hillsides at different altitudes are also different. Maple, birch, cypress, pine, cypress... Some of them are tall broad-leaved trees on the mountainside, and some are coniferous forests standing proudly on the top of the mountain. Between them, there are lush bushes. These plants densely cover the hills one after another. They grow vigorously in spring and summer, and begin a grand collective "change of clothes" in autumn.