7th Grade World History By omagid 500 BCE Trans-Saharan Trade Period: 500 BCE to 200 The Nok Period: 250 to 900 the Classical Maya period 300 Camels Arrive in West Africa 312 Roman Emperor Constantine begins to support Christianity 476 the Fall of Rome 610 Muhammad recieves first revelation 622 Muslims flee to Medina 629 Muslims retake Mecca 632 Muhammed dies Period: 632 to 661 the first four leaders of the Islamic Empire (the Rightly-Guided Caliphs)