From 1641 to 1663 in their new state at Matamba, Nzinga was viewed by the Portuguese as

b) to encourage free trade

the factors that the economies of the muslim empires prosper were:

1- land trade routes-located between three continents  

2- sea trade routes

trade contributed to the spread of muslim empires, and with that islamic culture led to a growing feeling of internationalism resulted in the transfer of technology, science, and other cultural forms.