The Republic of China was declared in 1911 after the ruling dynasty was overthrown. Stamps of the Chinese Imperial Post were overprinted in black or red. Sun Yat-sen, leader of the revolution, is pictured on many stamps. He often appears with the sun symbol of the Kuomintang (Nationalist) party, which he co-founded. Huge surcharges on stamps of 1948-49 (up to $5 million!) reflect the high rate of inflation. The government issued non-denominated stamps, sold at the daily value of the yuan. After World War II Communists split with the Nationalist government and began a guerilla war. Nationalists fled to Formosa (Taiwan) in 1949. Stamps of Taiwan are valid there and on surrounding islands.