End of the Long March and the Yan'an base

After a year-long retreat across western China, the Long March, the Red Army reached northern Shaanxi in October 1935 with perhaps a tenth of the troops who had set out. From 1937 to 1947 the Communists ran their territory from the loess caves of Yan'an, where Mao wrote key works and the 1942 Rectification Movement secured his authority. The caves are now a centre of 'red tourism'.