The Roman Empire began in 27 BCE when **Augustus** became the first emperor, marking the transition from the Roman Republic. The Empire expanded rapidly, dominating much of Europe, North Africa, and the Middle East. The **Pax Romana**, a 200-year period of relative peace, allowed the Empire to flourish economically, culturally, and militarily. Key emperors like **Trajan**, **Hadrian**, and **Constantine** contributed to its growth and stability. In 395 CE, the Empire split into the Western and Eastern Roman Empires. The Western Empire fell in 476 CE due to invasions and internal decline, while the Eastern Empire, or **Byzantine Empire**, lasted until 1453 CE.