Physiographic macroregions of China is a term suggested by an American anthropologist G. William Skinner as a subdivision of China Proper into nine areas according to the drainage basins of the major rivers and other travel-constraining geomorphological features. They are distinct in terms of environment, economic resources, culture and more or less interdependent histories with often unsynchronized developmental macrocycles. They were described in Skinner's landmark essays in The City in Late Imperial China.