Gansu is a province in the north west of the People's Republic of China that extends from the Mongolian border in the north to the geographic centre of China in the south. It provides a vital link between the upper Huang Ho (Yellow River) area in the east and Chinese Turkistan in the west. Gansu has a long history of international trade and transport because of its geographic link between east and west. The 2000-year-old Silk Road, the main trading route between China and Europe, passes through Gansu and many of the province's cities have grown up along it. The largest of these cities, Lanzhou, is now the provincial capital. Gansu occupies a huge area that incorporates many different climatic geographic regions, from well irrigated lowland plains to dry alpine regions. With a long history and brilliant cultures, Gansu is abundantly endowed with cultural relics and natural scenery. Vast and graceful natural scenery like endless desert and pure glacial landscape presents an impressive and breath-taking picture before your eyes. Take for example the world-famous Mogao Grottoes . It is the largest and most well-preserved Buddhist art palace and also a post along the ancient Silk Road; the grand Jiayuguan Pass , an important outpost in ancient China, is the western end of the Great Wall; the Labrang Monastery in Xiahe is one of the largest Tibetan Buddhist resorts in China while the Bingling Thousand Buddha Caves in Lanzhou are a treasure trove of Han Buddhism.