What factor(s) led to the fall of aksum?

After a second golden era in the beginning 6th century, the empire started to descend in the mid 6th century, ultimately terminating its generation of coins in the early 7th century. About this identical moment, the Aksumite community was seized to go far away inland to the mountains for camouflage, leaving Aksum as the center.

the answer to number 5 is fort sumter

a. the astrolabe could determine the correct latitudinal location of the ship