Then they were transferred to North Africa at some point in their respective careers .
In the 6th century , several prominent Byzantine military commanders had started their careers in the eastern regions of the Empire , often in the vicinity of Upper Mesopotamia .
Then military commanders were transferred to North Africa at some point in military commanders ' respective careers .
In the 6th century , several prominent Byzantine military commanders had started their careers in the eastern regions of the Empire , often in the vicinity of Upper Mesopotamia .