The fort was the first prefabricated building of European origin to have been planned and executed in Sub-Saharan Africa. Upon its completion, Elmina was established as a proper city. Azambuja was named governor, and King João added the title "Lord of Guinea" to his noble titles. São Jorge da Mina took on the military and economic importance that had previously been held by the Portuguese factory at Arguim Island on the southern edge of Mauritania. At the height of the gold trade in the early sixteenth century, 24,000 ounces of gold were exported annually from the Gold Coast, accounting for one-tenth of the world's supply.