Assuming the northern frontier was in Britain around Hadrian's Wall, the Romans called the Picts and the other tribes Caladonians.
The Romans built fortification along the frontiers of the empire and garrisons along the rivers Rhine and Danube, which formed inpatient stretches of the frontiers. They also stationed many legions in the frontier areas.
The Romans never conquered the Seleucid Empire.
Constantine's decision to designate Constantinople as the imperial capital did not have a great effect of Rome's position in the empire. Her position had been declining for some time. This was because the Romans had found it difficult to defend their frontiers along the rivers Rhine and Danube from numerous attempted invasions by outsiders. Since Rome was distant from these frontiers, she became marginalised. The frontiers areas became the important part of the empire and as a result of continuous military efforts to defend them, many emperors were humble men who had rose through the military ranks and were from Pannonia, an area along the mid-Danube. The importance of some cities along the Danube increased . Milan (in northern Italy) became very important because, being close to the Alps, it became the military base for sending troops to the frontiers along the Alps and the river Rhine and for the defence of northern Italy. Rome had already ceased to be the imperial capital under Diocletian, Constantine's predecessor. Diocletian had designated Nicomedia (in north-western Turkey) as the imperial capital for the eastern part of the Roman Empire and Milan as the imperial capital of the western part of the empire.
Computers and aircraft would have helped the Romans to rule their empire, big time.Computers and aircraft would have helped the Romans to rule their empire, big time.Computers and aircraft would have helped the Romans to rule their empire, big time.Computers and aircraft would have helped the Romans to rule their empire, big time.Computers and aircraft would have helped the Romans to rule their empire, big time.Computers and aircraft would have helped the Romans to rule their empire, big time.Computers and aircraft would have helped the Romans to rule their empire, big time.Computers and aircraft would have helped the Romans to rule their empire, big time.Computers and aircraft would have helped the Romans to rule their empire, big time.
Besides the legions, whose soldiers were Roman citizens, the Romans had auxiliary troops. These were soldiers supplied by the non-Romans of the provinces of the empire, which supported the legions. They supplied the bulk of the cavalry. The Romans also enlisted Germanic peoples who had been allowed to settle in northern Gaul or lived across the frontier of the empire as allies who also supported the legions. When necessary, the Romans also hired mercenaries.
Assuming the northern frontier was in Britain around Hadrian's Wall, the Romans called the Picts and the other tribes Caladonians.
The Romans built fortification along the frontiers of the empire and garrisons along the rivers Rhine and Danube, which formed inpatient stretches of the frontiers. They also stationed many legions in the frontier areas.
The biggest concerns of the Romans were protecting the vast frontiers of their empire from invasions and maintaining internal stability.
The Romans never conquered the Seleucid Empire.
The Roman army lost its discipline after the invasions of the empire, not before. This made the Romans unable to respond to the invasions. Prior to the invasions, the problems of the Roman army was that it was overstretched (due to many attempted invasions at points on the frontiers of the empire which were distant from each other) and that it had an insufficient number of soldiers. Due to the latter, the Romans recruited Germanic mercenaries and relied on Germanic allies in some areas.
Constantine's decision to designate Constantinople as the imperial capital did not have a great effect of Rome's position in the empire. Her position had been declining for some time. This was because the Romans had found it difficult to defend their frontiers along the rivers Rhine and Danube from numerous attempted invasions by outsiders. Since Rome was distant from these frontiers, she became marginalised. The frontiers areas became the important part of the empire and as a result of continuous military efforts to defend them, many emperors were humble men who had rose through the military ranks and were from Pannonia, an area along the mid-Danube. The importance of some cities along the Danube increased . Milan (in northern Italy) became very important because, being close to the Alps, it became the military base for sending troops to the frontiers along the Alps and the river Rhine and for the defence of northern Italy. Rome had already ceased to be the imperial capital under Diocletian, Constantine's predecessor. Diocletian had designated Nicomedia (in north-western Turkey) as the imperial capital for the eastern part of the Roman Empire and Milan as the imperial capital of the western part of the empire.
Computers and aircraft would have helped the Romans to rule their empire, big time.Computers and aircraft would have helped the Romans to rule their empire, big time.Computers and aircraft would have helped the Romans to rule their empire, big time.Computers and aircraft would have helped the Romans to rule their empire, big time.Computers and aircraft would have helped the Romans to rule their empire, big time.Computers and aircraft would have helped the Romans to rule their empire, big time.Computers and aircraft would have helped the Romans to rule their empire, big time.Computers and aircraft would have helped the Romans to rule their empire, big time.Computers and aircraft would have helped the Romans to rule their empire, big time.
Besides the legions, whose soldiers were Roman citizens, the Romans had auxiliary troops. These were soldiers supplied by the non-Romans of the provinces of the empire, which supported the legions. They supplied the bulk of the cavalry. The Romans also enlisted Germanic peoples who had been allowed to settle in northern Gaul or lived across the frontier of the empire as allies who also supported the legions. When necessary, the Romans also hired mercenaries.
Barbarian was a word which the Romans adopted from the Greeks and meant foreigner. For the Greeks it referred to anyone who did not speak Greek. Originally the Roman use of the term barbarian referred to non-Romans. When Roman citizenship was extended to all freemen in the Roman Empire by the emperor Caracalla in 215, and all the conquered peoples became Romans, barbarian came to refer to the peoples who lived outside the Roman Empire. Therefore, the barbarians came to be the peoples who lived on the other side of the frontiers of the Roman Empire: north-western Europe, eastern Europe, Persia, Arabia and Africans who lived south of the border of the empire.
The Romans didn't have a name for the continent of Africa, as we do, but one of the provinces of the empire was named Africa. The other provinces in the northern part of what we call Africa were, Egypt (Aegyptus) Cyrenaica, Numidia and Mauritania.
They were the nomadic peoples of Eurasia who threatened the security of the Empire. As they moved into the empire they became settled and civilised, eventually becoming Roman citizens until they took over the Western Empire.
The Byzantine empire was the continuation of the Roman Empire.