What are the defining characteristics of the sprawling era known as the Middle Ages? What sets ancient Egypt apart from other ancient civilizations? And what is the legacy of the twentieth-century genocide known as the Holocaust? These are some of the ideas explored in Understanding World History, a series that surveys the political, social, and cultural trends of major periods and events in world history. Primary and secondary source quotes bring historical events to life. Source notes, a bibliography for further research, and index provide additional tools for student researchers.