The eastern part of the Empire did not have the privilege of ruling the whole Mediterranean. After the collapse of Rome, Byzantium continued the tradition of the Roman Empire, constantly attempting to restore its glory. Without the power and the control of the old Roman Empire, Byzantium had to revert to diplomacy to a greater extent. Surrounded by hostile tribes in the Balkans, Asia, the Middle East, and Africa, it used sophisticated techniques to keep them under control.
The over-extension of the Byzantine Empire, required geographically broad diplomatic coverage, from China and India in the east, to the Atlantic Ocean in the west, from the interior of Africa to the steppes of the Black Sea.
Concerning diplomatic practice, Byzantium took the first step towards establishing an apparatus for managing foreign relations, some sort of early Ministry of Foreign Affairs. Byzantium also made use of international agreements. One of its most developed treaty practices was with Russian rulers. The first treaty was signed with Oleg (911 A.D.), a later one with Igor (944 A.D.). Treaties had very broad coverage, including many provisions on cooperation in “criminal affairs,” including the Russian right to extradition from Byzantium of any of its subjects who committed a criminal act.