Egypt is the fifteenth most populous country in the world. The vast majority of its 78.8 million population (2006)[1] live near the banks of the Nile River (about 40,000 km² or 15,450 sq miles) where the only arable agricultural land is found.The regularity and richness of the annual Nile River flood, coupled with semi-isolation provided by deserts to the east and west, allowed for the development of one of the world's great civilizations. A unified kingdom arose circa 3200 B.C., and a series of dynasties ruled in Egypt for the next three millennia. The last native dynasty fell to the Persians in 341 B.C., who in turn were replaced by the Greeks, Romans, and Byzantines.
It was the Arabs who introduced Islam and the Arabic language in the 7th century and who ruled for the next six centuries. A local military caste, the Mamluks took control about 1250 and continued to govern after the conquest of Egypt by the Ottoman Turks in 1517. Following the completion of the Suez Canal in 1869, Egypt became an important world transportation hub, but also fell heavily into debt.
Large areas of land form part of the Sahara Desert and are sparsely inhabited. Around half of Egypt's residents live in urban areas, with the majority spread across the densely populated centres of greater Cairo (the largest city in Africa and the Middle East), Alexandria and other major towns in the Nile Delta.