The very weak Portuguese position in Upper Guinea was strengthened by the first Marquess of Pombal who promoted the supply of slaves from this area to the provinces of Grão-Pará and Maranhão in northern Brazil, and between 1757 and 1777, over 25,000 slaves were transported from the “Rivers of Guinea”, which approximates Portuguese Guinea and parts of Senegal, although this area had been largely neglected by the Portuguese for the previous 200 years. Bissau, founded in 1765, became the centre of Portuguese control.