How did Byzantium solve the social problems caused by the mass movement of Slavs?

If after the middle of the 6th century, the Slavic tribes going south from the Danube to the Balkans were regarded as a kind of blind population movement, then the migration policy adopted by Byzantine government was to reorganize this unorganized population movement in the military region, and by retaining and promoting the Slavic rural commune system, the social problems caused by the Slavic mass movement were solved according to the situation.