These deprived the East Roman empire of its dominions in the Middle East and North Africa , especially Egypt .
The Eastern empire and army , on the other hand , continued with gradual changes until the Persian and later Arab invasions in the 7th century .
These deprived the Eastern empire     of its dominions in the Eastern empire   and North Africa , especially Egypt .
The Eastern empire and army , on the other hand , continued with gradual changes until the Persian and later Arab invasions in the 7th century .