What if Some of the Eastern Slavs migrated to Sassanid Persia and pillaged it at the same time as the Caliphate invades Persia, ITTL there will be no expansion of the Slavs to the Balkans.
What if Some of the Eastern Slavs migrated to Sassanid Persia and pillaged it at the same time as the Caliphate invades Persia, ITTL there will be no expansion of the Slavs to the Balkans.