<P> Portugal's main goal on the Swahili coast was to take control of the spice trade from the Arabs . At this stage, the Portuguese presence in East Africa served the purposes of controlling trade within the Indian Ocean and securing the sea routes linking Europe to Asia . Portuguese naval vessels were very disruptive to the commerce of Portugal's enemies within the western Indian Ocean and were able to demand high tariffs on items transported through the sea due to their strategic control of ports and shipping lanes . The construction of Fort Jesus in Mombasa in 1593 was meant to solidify Portuguese hegemony in the region, but their influence was clipped by the British, Dutch and Omani Arab incursions into the Great Lakes region during the 17th century . </P> <P> The Omani Arabs posed the most direct challenge to Portuguese influence in the African Great Lakes regigon . They besieged Portuguese fortresses, openly attacked naval vessels and expelled the Portuguese from the Kenyan and Tanzanian coasts by 1730 . By this time, the Portuguese Empire had already lost its interest on the spice trade sea route due to the decreasing profitability of that business . The Arabs reclaimed much of the Indian Ocean trade, forcing the Portuguese to retreat south where they remained in Portuguese East Africa (Mozambique) as sole rulers until the 1975 independence of Mozambique . </P> <P> Omani Arab colonization of the Kenyan and Tanzanian coasts brought the once independent city - states under closer foreign scrutiny and domination than was experienced during the Portuguese period . Like their predecessors, the Omani Arabs were primarily able only to control the coastal areas, not the interior . However, the creation of clove plantations, intensification of the slave trade and relocation of the Omani capital to Zanzibar in 1839 by Seyyid Said had the effect of consolidating the Omani power in the region . </P> <P> Arab governance of all the major ports along the Swahili coast continued until British interests aimed particularly at ending the slave trade and creation of a wage - labour system began to put pressure on Omani rule . By the late nineteenth century, the slave trade on the open seas had been completely outlawed by the British and the Omani Arabs had little ability to resist the British navy's ability to enforce the directive . The Omani presence continued in Zanzibar and Pemba until the Zanzibar Revolution in 1964 . However, the official Omani Arab presence in Kenya was checked by German and British seizure of key ports and creation of crucial trade alliances with influential local leaders in the 1880s . </P>

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