Zhangye originally was founded as one of the many forts and trading-posts along the silk road between its origins at Xi'an and the great fort at Jiayuguan where it moved on westwards across the dangerous and inhospitable desert. As a fort and trading-post Zhangye isn't specially notable, but a short distance away lie the Rainbow Mountains, a dramatic area of rugged mountains and vibrant rocks.

The great fort at Jiayuguan lies at the western end of the Great Wall, over 1000 miles from Beijing. The fort commands the entrance from the desert eastwards into the narrow valley between the Qilian and Mazong Mountains which led inland toward Xi'an and, for many years, China proper. To the west lay desert, barbarians and warlords, and the fort occupied the strategic point at which to prevent the entry of enemies, especially the Mongols, who could threaten imperial China. Although some form of fort existed here for a 1000 years, the present fort was constructed by the Ming dynasty in the 14th century, with walls 35 feet high, anchoring the western end of the Great Wall.

From Jiayuguan the traveller on the southern silk road would now make the three week journey to the first major oasis in the desert at Dunhuang. Dunhuang was a major trading and re-supply post on the silk road from it's original conception, a vital stop-over for travelers and caravans in either direction. It's importance meant that control of the town was fought over my many competing interests -- originally ruled by the Han Chinese in the 1st century BC, followed by Tibetans, Mongols, and Ughurs, each on multiple occasions, eventually ending up under Chinese control again in the 18th century.

The enormous sand dunes rise over 1000 feet and were referred to by Marco Polo as the "rumbling sands" as they are always on the move and make drum-like sounds as the wind sweeps over them. Yet, despite this, Crescent Moon Lake has always survived as a focal point of the oasis and has never been covered or enroached upon by the moving sands. Today tourists can relive the delights of the travelers in the ancient caravans by taking rides on the dunes on the same Bactrian camels!