Byzantine Empire and Roman Empire

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 Roman Empire was a state that dominated the Mediterranean and much of Europe, Western Asia, and North Africa during the classical period. The Roman Republic had previously conquered most of these territories, which later came under permanent single-person rule following Octavian's rise to power and the establishment of the Augustan Principate in 27 BC. By the late 3rd century AD, the empire had been divided many times. The Western Roman Empire collapsed in 476 AD, whereas the Eastern Roman Empire (also known as the Byzantine Empire) persisted until the fall of Constantinople in 1453.