The monogenetic theory of pidgins and creoles hypothesizes that they are all derived from a single Mediterranean Lingua Franca, via a West African Pidgin Portuguese of the 17th century, relexified in the so-called "slave factories" of Western Africa that were the source of the Atlantic slave trade.
Proposed by for the origin of English-based creoles of the West Indies, the Domestic Origin Hypothesis argues that, towards the end of the 16th century, English-speaking traders began to settle in the Gambia and Sierra Leone rivers as well as in neighboring areas such as the Bullom and Sherbro coasts.