Yan Xishan was a Chinese warlord who served in the government of the Republic of China. He effectively controlled the province of Shanxi from the 1911 Xinhai Revolution to the 1949 Communist victory in the Chinese Civil War. As the leader of a relatively small, poor, remote province, he survived the machinations of Yuan Shikai, the Warlord Era, the Nationalist Era, the Japanese invasion of China and the subsequent civil war, being forced from office only when the Nationalist armies with which he was aligned had completely lost control of the Chinese mainland, isolating Shanxi from any source of economic or military supply. He has been viewed by Western biographers as a transitional figure who advocated using Western technology to protect Chinese traditions, while at the same time reforming older political, social and economic conditions in a way that paved the way for the radical changes that would occur after his rule.