Explore Tham Ma Slope - Ha Giang Travel Doc Tham Ma is a winding pass road located on Highway 4c running from this land to Meo Vac district. Tham Ma Slope is an extremely famous nine-turn pass here. This is a familiar route for young people who love to explore, like to conquer adventures and admire the majestic natural beauty. when coming to the land of the fatherland. This famous slope takes visitors on a journey to the first gateway on Dong Van land - Pho Cao commune, which is also a famous tourist destination in the Stone Highlands area.