1.2 Discovery of America(1492) Maritime revolution* Portuguese女 Christopher Columbus (1451-1506)* The Americas★ Columbus's“discovery”★ Zheng He and Seven Expeditions to "The Nestern Ocean”★1.2 Discovery of America (1492) 1.2 Discovery of America (1492) Maritime revolution ★ Portuguese Portuguese ★ Christopher Columbus (1451–1506) ★ The Americas ★ Columbus’s “discovery” ★ Zheng He and Seven Expeditions to He and Seven Expeditions to “The Western Ocean Western Ocean ” ★