Egypt's history spans thousands of years, beginning with the unification of Upper and Lower Egypt around 3100 BCE under the first pharaoh, Narmer. The civilization flourished along the Nile River, known for its monumental architecture, including the Pyramids of Giza and the Sphinx. Ancient Egyptians developed a complex society with advancements in writing, mathematics, and medicine. Throughout its history, Egypt experienced periods of prosperity and decline, influenced by invasions and foreign rule, including the Persians, Greeks, and Romans. The rise of Islam in the 7th century CE marked a significant cultural shift, leading to the establishment of Cairo as a major center of learning and trade.