The entourage of the emperor dominated the imperial courts of both the western part of the Roman Empire and the eastern part of the Roman Empire in antiquity and the Holy Roman Empire of the Middle Ages.
The capital of the Roman Empire was not moved from Rome to Constantinople. Rome had already ceased to be the imperial capital under Constantine's predecessor, Diocletian. He designated Nicodemia (in north-western Turkey) as the imperial capital of the eastern part of the Roman Empire and Milan (in northern Italy) as the imperial capital of the western part. Constantinople was just 60 miles to the west of Nicodemia. Constantine's designation of Constantinople as his imperial capital did not weaken the western part of the empire. Diocletian had created a co-emperorship with his fellow general Maximian. Diocletian was in charge of the eastern part of the empire and resided in Nicomedia. Maximian was in charge of the western part and resided in Milan. After winning tow civil wars, Constantine became sole emperor. Therefore, one imperial capital was sufficient and no parts of the empire were weakened.
The capital of the Roman Empire was not moved from Rome to Constantinople. Rome had already ceased to be the imperial capital under Constantine's predecessor, Diocletian. He designated Nicodemia (in north-western Turkey) as the imperial capital of the eastern part of the Roman Empire and Milan (in northern Italy) as the imperial capital of the western part. Constantinople was just 60 miles to the west of Nicodemia. Constantine's designation of Constantinople as his imperial capital did not weaken the western part of the empire. Diocletian had created a co-emperorship with his fellow general Maximian. Diocletian was in charge of the eastern part of the empire and resided in Nicomedia. Maximian was in charge of the western part and resided in Milan. After winning tow civil wars, Constantine became sole emperor. Therefore, one imperial capital was sufficient and no parts of the empire were weakened.
Your question is very unclear. Constantinople was a Roman city, it was the imperial capital of the eastern part of the Roman Empire (the imperial capital of the western part of the Roman Empire was Milan).
There was not a northern part of the Roman Empire. There were a western and an eastern part. In 286 emperor Diocletian designated Milan as the imperial capital of the western part and Nicomedia (in northwestern Turkey) as the imperial capital of the eastern part. In 330 Constantine I moved the imperial capital of the eastern part to the nearby Byzantium, which he redeveloped and renamed Constantinople. On 402 emperor Honorius moved the imperial capital of the western part to Ravenna, also in Italy.
The Songhai Empire (also transliterated as Songhay) was a state that dominated the western Sahel in the 15th and 16th century. Its capital was Gao.
The British Empire
Women in early 20th-century England demand the right to vote, but their government refuses to allow it.
Imperial Order of the Daughters of the Empire was created in 1900.
The Spanish Empire. Prior to them it was the Aztec Empire.
The Mughal Empire
Constantine the Great designated Byzantium as his imperial capital, redeveloped it and renamed it Constantinople (City of Constantine). Contrary from it is sometimes though, he did not move the capital from Rome. Rome had already ceased to be the imperial capital under Constantine's predecessor, Diocletian, who designated Nicomedia (in north-western Turkey, not far from Byzantium) as the imperial capital of the eastern part of the Roman Empire and Milan (in northern Italy) as the imperial capital of the western part of the empire.
Austrians