From the Fouta Djallon, it runs northwest into the Tambacounda Region of Senegal, where it flows through the Parc National du Niokolo Koba, then is joined by the Nieri Ko and Koulountou [fr] and passing through the Barrakunda Falls before entering the Gambia at Koina.

[5] According to oral tradition, large numbers of Mandinka immigrants from Mali led by Tiramakhan Traore, one of Sundiata's top generals, came to the region in the 14th century.

Some modern historians, however, posit that relatively few immigrants, primarily jula traders, instead led a gradual socio-cultural shift towards identification with the higher-status Mandinka ethnicity and the ruling Mali Empire.

[6][7] These jula made the Gambia an important part of the wider West African trade network, where salt, shellfish, iron, cloth, ivory, beeswax, gold, slaves, leather and more were exchanged as far as the Niger River and beyond.

[8][9] Alvise Cadamosto, a Venetian explorer working for the Portuguese, became the first European to sail to the Gambia in 1455, referring to the river as the Gambra or Cambra.

[10] While merchants of various European countries traded on the Gambia river for two centuries after Cadamosto, the Duchy of Courland and Semigallia was the first to establish a permanent base, on what they called St Andrew's Island in 1651.