Byzantine Empire and Umayyad Caliphate

The Byzantine Empire, also known as the Eastern Roman Empire, was the continuation of the Eastern part of the Roman Empire centred on Constantinople during late antiquity and the Middle Ages. Having survived the fall of the Western Roman Empire in the 5th century AD, it endured until the fall of Constantinople to the Ottoman Empire in 1453. The term 'Byzantine Empire' was coined only after its demise; its citizens used the term 'Roman Empire' and called themselves 'Romans'.

The Umayyad Caliphate, or the Umayyad Empire (US: ; Arabic: ٱلْخِلَافَة ٱلْأُمَوِيَّة, romanized: al-Khilāfa al-Umawiyya), was the second Islamic caliphate, ruled by the Umayyad dynasty from 661 to 750. It succeeded the Rashidun Caliphate, whose third caliph, Uthman ibn Affan (r. 644–656), was also a member of the Umayyad clan. The Umayyad family established hereditary rule under Mu'awiya ibn Abi Sufyan, the long-time governor of Syria, who became caliph in 661 after emerging victorious in the First Fitna. Syria served as the caliphate's metropolitan province thereafter, with Damascus as its capital.