All the other answers would raise the death rate, except for 3, but that wouldn't have such a profound impact to where the death rate would decrease by a substantial amount
The Barbary coastal states of north Africa involves the morocco and the state of Tripoli and were used by the European in the 16th century and it refers to the coastal states of the North Americas and the regions of the North Africa that are home to the Berber people today. Barbary was a political entity and was were divided by the monarchs.
