China's landscape is vast and diverse. It ranges from the Gobi and Taklamakan Deserts in the north to subtropical forests in the south. The Himalaya, Karakoram, Pamir and Tian Shan mountain ranges separate China from much of South and Central Asia. The Yangtze and Yellow Rivers run from the Tibetan Plateau to the densely populated eastern coast. The Yangtze River is the third-longest river in the world while the Yellow River is the sixth-longest. China's coastline along the Pacific Ocean is 14,500 kilometers (9,000 mi) long. It is bounded by the Bohai, Yellow, East China and South China seas. China connects through the Kazakh border to the Eurasian Steppe. The Eurasian Steppe has been an artery of communication between East and West since the Neolithic through the Steppe route. The Steppe Route is the ancestor of the terrestrial Silk Road(s).