sentences:  In 1698, Zanzibar became part of the overseas holdings of Oman after Saif bin Sultan, the Imam of Oman, defeated the Portuguese in Mombasa, in what is now Kenya.In 1832 or 1840, Omani ruler Said bin Sultan moved his court from Muscat to Stone Town on the island of Unguja (that is, Zanzibar Island).He established a ruling Arab elite and encouraged the development of clove plantations, using the island's slave labour.