 During this time, industrialization was slow to non-existent; between the years 1920 and 1949, the industrial sector had only increased by less than three million members, mainly women and children working in cotton mills.The main changes in social structure were military.In 1924, the Soviet Union helped Sun Yat-sen rebuild the Nationalist Kuomintang, GMT, and KMT military force, most notably through the Military Academy, an island on Pearl River near Guangzhou.