In consequence of this, Moçambique and the Zambezi for some years replaced West Africa as a slave market. In 1649 the English first made their appearance on this coast; and two years afterwards the Portuguese were perturbed by the definite establishment of a Dutch colony at the Cape, and by the establishment of French factories on the coast of Madagascar—events which are prophetically described by a contemporary writer as “Quantos passos para a ruina de Moçambique!”—“So many steps towards the ruin of Moçambique!” At the same time the Arabs in the Persian Gulf drove the Portuguese out of Maskat, and towards the end of the 17th century began to attack their possessions on the Zanzibar coast. By 1698 Portugal had lost every fortress north of Moçambique; and in that year this, their last stronghold, was besieged straitly by the Arabs and very nearly captured. In fact it was only saved by the friendly treachery of an Indian trader who warned the Portuguese of an intended night attack. All of these posts on the Zanzibar coast were finally abandoned[71] by the Portuguese in the early part of the 18th century by agreement with the Imam of Maskat, who founded the present dynasty of Zanzibar. In 1752 this fact was recognized by the formal delimitation of the Portuguese possessions in East Africa at the time when they were also again removed from any dependency on the Governor of Goa. In this decree of the 19th of April, 1752, the government of Moçambique was described as extending over “Moçambique, Sofala, Rio de Sena (Zambezi), and all the coast of Africa and its continent between Cape Delgado and the Bay of Lourenço Marquez (Delagoa Bay).” Hitherto commerce in Portuguese East Africa had been singularly restricted, and after being first confined to the Governors and officials of the state, was then delegated to certain companies to whom monopolies were sold. In 1687 there was a fresh arrival, after a considerable interval, of Indian traders, who established themselves on the Island of Moçambique; and by degrees the whole of the commerce of Portuguese East Africa was thrown open freely to all Portuguese subjects, though it was absolutely forbidden to the subjects of any other European power, and considerable anger was displayed when French and Dutch endeavoured to trade on the islands or on the coast in the province of Moçambique. In the middle of the 18th century the practice of sending the worst stamp of Portuguese convicts to Moçambique was unhappily adopted in spite of the many protests of its governors. About this same time also there occurred a series of disasters attributable to the deplorable mismanagement of the Portuguese officials. The fortresses of the gold-mining country of Manika had to be abandoned, like Zumbo[72] on the upper Zambezi. The forts on