Ottoman Empire

The Ottoman Empire's 623-year lifespan makes it history's longest-lived major empire. At its peak under Suleiman the Magnificent (1520-1566), it spanned 5.2 million square kilometres across three continents, with a population of approximately 30 million. The empire's collapse after World War I directly created most modern Middle Eastern borders—and many of today's regional conflicts. Its legal and administrative systems, including the millet system of religious tolerance, influenced successor states for decades.