Clothes must be washed frequently since the slightest breeze blows up a cloud of fine dust in the loessal highlands of North China. The walls of the ancient capital city of Sian (upper left) are 50 feet high and 20 feet thick and are perhaps the best preserved of all the remaining city walls in China today. Forman 1792: City walls of Sian, Shensi [Shaanxi] province. Sian was the capital of Imperial China for almost 2,000 years before the empire fell to the Mongols and, later, the Manchus.
