West of the Huang He (Yellow River) in northeast Gansu province is a long corridor passage that connects China and Central Asia. This is the 1200 km-long Hexi Corridor, a renowned section of the northern Silk Road that traverses through the Gobi desert. At the center of the corridor is the city of Zhangye where Marco Polo spent a year, according to his Travels. This is also an area of surreal beauty due to the striated rock formations that give the mountain range rainbow-like colors.
Ancient grottoes and fortresses, including the best preserved parts of the Great Wall of China, dot this vast arid region that was, until the rise of maritime trade in the 14th century, the artery of trade and cultural exchange across three continents: Asia, Europe and Africa.