By 1964, the country was a constitutional monarchy ruled by Sultan Jamshid bin Abdullah. Zanzibar had a population of around 230,000 Africans—some of whom claimed Persian ancestry and were known locally as Shirazis—and also contained significant minorities in the 50,000 Arabs and 20,000 South Asians who were prominent in business and trade. The various ethnic groups were becoming mixed and the distinctions between them had blurred; according to one historian, an important reason for the general support for Sultan Jamshid was his family's ethnic diversity. However, the island's Arab inhabitants, as the major landowners, were generally wealthier than the Africans; the major political parties were organised largely along ethnic lines, with Arabs dominating the Zanzibar Nationalist Party (ZNP) and Africans the Afro-Shirazi Party (ASP). The ZNP looked towards Egypt as its model, which caused some tensions with the British colonial officials, but Zanzibar had been for centuries dominated by its Arab elite, and the Colonial Office could not imagine a Zanzibar ruled by the blacks.