Astapor, home of the Unsullied, lies on the cliffs of Slaver's Bay. Beaten by the winds of the Summer Sea. Beyond the walls, the Good Masters train the best infantry of the known world: the Unsullied. Where Daenerys ended up buying 8,600 of them to join her forces.
The most awesome part? She released her newly bought slaves afterwards and sacked the city of Astapor, killing the slave masters in the process.