The Hexi Corridor (, Xiao'erjing: حْسِ ظِوْلاْ, IPA: ), also known as the Gansu Corridor, is an important historical region located in the modern western Gansu province of China. It refers to a narrow stretch of traversable and relatively arable plain west of the Yellow River's Ordos Loop, flanked between the much more elevated and inhospitable terrains of the Mongolian and Tibetan Plateaus. The name Hexi, refers to "west of the river". As part of the Northern Silk Road, running northwest from the western section of the Ordos Loop between Yinchuan and Lanzhou, the Hexi Corridor was the most important trade route in Northwest China. It linked China proper to the historic Western Regions for traders and military incursions into Central Asia. It is a string of oases along the northern edges of the Qilian Mountains and Altyn-Tagh, with the high and desolate Tibetan Plateau further to the south. To the north are the Longshou, Heli and Mazong Mountains separating it from the arid Badain Jaran Desert, Gobi Desert and the cold steppes of the Mongolian Plateau. At the western end, the route splits into three, going either north of the Tianshan Mountains or south on either side of the Tarim Basin. At the eastern end, the mountains around Lanzhou grants access to the Longxi Basin, which leads east through Mount Long along the Wei River valley into the populous Guanzhong Plain, and then into the Central Plain. History Early crop dispersal Chinese millets (Panicum miliaceum, and Setaria italica), rice, and other crops travelled westwards through the Corridor, and reached Western Asia and Europe from the fifth millennium to the second millennium BC. Cultivated wheat, originating at the Fertile Crescent, appeared in China around 2800 BC at Donghuishan at the Hexi corridor. Several other crops are also attested at this time period. Xishanping is another similar site in Gansu. According to Dodson and coauthors (2013), wheat entered via the Hexi Corridor into northern Gansu around 3000 BC, although other scholars date this somewhat later. As early as the 1st millennium BCE, silk goods began appearing in Siberia, having traveled over the northern branch of the Silk Road, including the Hexi Corridor segment. Qin dynasty At the end of the Qin dynasty (221–206 BCE), the Yuezhi overcame previous settlers, the Wusun and Qiang, occupying the western Hexi Corridor. Later, the newly risen Xiongnu armies under Modu Chanyu vanquished and expelled the