In this state Zanzibar remained till the close of the next century. When, however, Pedro Barrato de Rezende, Secretary to the Viceroy, Count of Linhares, wrote his ‘Breve Tratado’ on the Portuguese colonies of India and East Africa (1635), the Island had ceased to be vassal and tributary, but the Sultan remained friendly to Europeans. Many of the latter occupied with their families rich plantations; Catholic worship was protected, and there was a church in which officiated a brother of the order of St Austin. There was the usual massacre of the Portuguese, and expulsion of the survivors in imitation of Mombasah, about 1660; and the Islanders, doubting their power to procure independence, applied for assistance to the Arabs. The reign of the Yu’rabi of Oman, a clan of the great Ghafiri tribe, began as follows. The Imam, Sultan bin Sayf bin Malik el Yu’rabi, the second of the family, having recovered Maskat (April 23, 1659), and Matrah, created a navy which added Kang, Khishm, Hormuz, Bahrayn, and Mombasah (1660) to the Arabian possessions left by his ancestors. After investing Bombay this doughty chief died in A.D. 1668 or in 1669. His son, Sayf bin Sultan, after defeating an elder brother, Belárab, became the third Imam of the house of Yu’rabi, and summoned to submission the petty chiefs on the eastern mainland of Africa. Between A.D. 1680 and 1698, the powerful squadron of the warlike Moor drove the Portuguese from Zanzibar, Kilwa, Pemba, and Mombasah, where he established as Governor Nasir bin Abdillah el Mazru’i, the first of the great family of that name. He failed only at Mozambique. Arabs still relate the legend how having closely invested the fort they were undermining the wall, when a Banyan gave traitorous warning to the besieged. Pans of water ranged upon the ground showed by the trembling fluid the direction of the tunnel; a countermine was sprung with fatal effect, and the assailants, retreating in confusion to their shipping, raised the siege.[76] The squadron, however, pursued its course as far south as the Comoros and Bukini (Madagascar, or rather the northern portion of the Island), whence, hearing of the ruler’s death, it returned home. When the Island became Arab property the Wasawahili fled to the ‘bush’: they presently consented to render personal service, or to purchase exemption by annually paying $2 per head.