Yaan is located at the intersection of Sichuan-Tibet Highway and Sichuan-Yunnan Highway, 120km away from Chengdu. It is the transition zone between Sichuan Basin and Qinghai-Tibet Plateau, the Han culture and ethnic minority culture, and the modern center city and primitive ecological zone. It was the portal and necessary route of Ancient Southern Silk Road and the capital city of Xikang Province. Yaan is a famed historical and cultural city and an emerging tourism city in Sichuan Province, known as the "City of Rain". The municipal administrative area is in an irregular pattern with longer north-south area and narrower east-west area with Aba Tibetan and Qiang Autonomous Prefecture at its north, Ganzi Tibetan Autonomous Prefecture and Liangshan Yi Autonomous Prefecture at its west and south, and Chengdu, Meishan and Leshan at its east. In general, Yaan is adjacent to Chengdu, Ganzi Prefecture, Liangshan Prefecture and Aba Prefecture to the east, west, south and north respectively with reputations of "Western Sichuan Throat," "Tibet Portal" and "Ethnic Corridor."