A map depicting the legion HQ and fortresses during Trajan’s reign (AD 98–117). Trajan was one of the greatest Roman emperors and in general Roman personalities. During his reign, the Roman Empire reached its greatest extent. Note that

the legion camps are more dense in the Danube valley and also in Syria and Palestine where Rome faced the greatest threats by its enemies: free Dacians, Germanics and Parthians. Actually the Dacian kdm was destroyed by Rome and a large part of it was annexed. The Romans also occupied Parthian Mesopotamia for a few decades.