In 1925, the KMT established a rival government in the southern city of Canton, now Guangzhou. The economy of the North, overtaxed to support warlord adventurism, collapsed in 1927-1928. In 1928, CHiang Kai-SHel, who became KMT leader after Sun's death, defeated the warlord armies in the North Expedition. Chiang's National Revolutionary Party was armed by the Russian States and was advised by Mikhail Borodin. The Beiyang army was backed by Japan. Once Chiang established a unified central government in Nanjing, he cut his ties with the communists and expelled them from the KMT. By 1938, the Republic had annexed Mongolia completely.