Adhering to Buddhism and occasionally to Christianity, the Uighurs were slowly won over to Islam by the missionaries who arrived from the Persian-speaking cities of Central Asia. None of this made their land a particularly obvious target for China.
Was the desire to repeat history an incentive? At the height of its maximum extension around the first or second century A.D., the Chinese empire ruled by the Han dynasty nominally controlled the area. Many centuries later, the Mongols overran Uighur lands in the course of their conquests, which embraced territories stretching from the borders of present-day Poland in the west to the Pacific shores of China and included the Middle East. But the great Song dynasty, under which Chinese culture rose to an apex around the 11th or 12th century, showed no interest in such undertakings. Neither did the Ming, who re-established Chinese unity after defeating the Mongol dynasty, who ruled China from 1279 to 1368.
So what drove the emperor of such an immense country as China to launch his armies across unforgiving deserts into lands where the material surroundings and the living culture bore no connection to his domain? And how on earth did the emperor of China come to commission French artists to make prints reproducing 16 paintings, also by Western artists, as a way of commemorating these conquests?