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 often been divided. The later Western Roman Empire collapsed in 476 AD, whereas the Eastern Roman Empire persisted until the fall of Constantinople in 1453.