Furthermore , the Sasanians and Avars had difficulties communicating across the guarded Bosphorus -- though undoubtedly , there was some communication between the two forces .
This reduced the effectiveness of the siege , because the Sasanians were experts in siege warfare .
Furthermore , the experts and Avars had difficulties communicating across the guarded Bosphorus -- though undoubtedly , there was some communication between the two forces .
This reduced the effectiveness of the siege , because the Sasanians were experts in siege warfare .