A major historian of ancient times was Julius Caesar, the general who became Rome's first emperor. His histories included an account of his invasion of Britain. To make sense out of the thousands of years of human history, historians have divided the past into periods. The Middle Ages is the name we give to the period of time between Ancient and Modern history. Ancient history is the story of classical Greece and Rome. Modern history is the story of the period following the Renaissance, the Reformation and the discovery of the Americas. Such divisions are not exact, and in fact may overlap considerably. These are divisions invented by historians simply to help us understand the past. Later historians, with different points of view, may invent new period divisions.