The post of Sultan of Zanzibar was created on 19 October 1856, after the death of Sa'id ibn Sultan, who had ruled Oman and Zanzibar as the Sultan of Oman since 1804. The Sultans of Zanzibar were of a cadet branch of the Al Bu Sa'id Dynasty of Oman. In December 1963, Zanzibar was granted independence by the United Kingdom and became a constitutional monarchy under the sultan. The sultan, Jamshid ibn Abdullah, was overthrown a month later during the Zanzibar Revolution.