The Roman Empire was divided into Eastern and Western regions during the fourth century AD. This division occurred under the reign of Emperor Diocletian, who aimed to make administration more efficient by creating a system of governance that could oversee the vast territories more effectively. The Eastern Roman Empire, often referred to as the Byzantine Empire, continued to thrive for nearly another thousand years after the fall of the Western Empire in 476 AD. This division had profound implications for both regions, influencing culture, politics, and religion, and laid the groundwork for the development of distinct European and Middle Eastern histories.