Ottoman Turks, Portugal hoped to use the sea route pioneered by da Gama to break the Venetian trading monopoly. Initially, Portuguese rule in East Africa focused mainly on a coastal strip centred in Mombasa. With voyages led by Vasco da Gama, Francisco de Almeida and Afonso de Albuquerque, the Portuguese dominated much of southeast Africa's coast, including Sofala and Kilwa, by 1515. Their main goal was to dominate trade with India. As the Portuguese settled along the coast, they made their way into the hinterland as (backwoodsmen). These lived alongside Swahili traders and even took up service among Shona kings as interpreters and political advisors. One such managed to travel through almost all the Shona kingdoms, including the Mutapa Empire's (Mwenemutapa) metropolitan district, between 1512 and 1516. By the 1530s, small groups of Portuguese traders and prospectors penetrated the interior regions seeking gold, where they set up garrisons and trading posts at Sena and Tete on the Zambezi River and tried to gain exclusive control over the gold trade. The Portuguese finally entered into direct relations with the Mwenemutapa in the 1560s. They recorded a wealth of information about the Mutapa kingdom as well as its predecessor, Great Zimbabwe. According to Swahili traders whose accounts were recorded by the Portuguese historian João de Barros, Great Zimbabwe was an ancient capital city built of stones of marvellous size without the use of mortar. And while the site was not within Mutapa's borders, the Mwenemutapa kept noblemen and some of his wives there. The Portuguese attempted to legitimate and consolidate their trade and settlement positions through the creation of (land grants) tied to Portuguese settlement and administration. While were originally developed to be held by Portuguese, through intermarriage they became African Portuguese or African Indian centres defended by large African slave armies known as Chikunda. Historically, within Mozambique, there was slavery. Human beings were bought and sold by African tribal chiefs, Arab traders, and the Portuguese. Many Mozambican slaves were supplied by tribal chiefs who raided warring tribes and sold their captives to the . Although Portuguese influence gradually expanded, its power was limited and exercised through individual settlers and officials who were granted extensive autonomy. The Portuguese were able to wrest much of the coastal trade from Arabs between 1500 and 1700, but, with the Arab seizure of Portugal's key foothold at Fort Jesus on Mombasa Island (now in Kenya) in