The call for revival of the sultanate continued throughout the period of autonomous rule under the Riau Council, although the influence of republicanism also continued to strengthen. The appeal of revival began to subside following the dissolution of the "Bangka Belitung and Riau Federation" on 4 April 1950. After the official withdrawal by the Dutch in 1950, the Riau Archipelago became "Keresidenan Riau" under Central Sumatra Province following the absorption by the United States of Indonesia. Being one of the last territories merged into Indonesia, Riau was known as the "daerah-daerah pulihan" (recovered regions), and the Riau area became a province in August 1957.