Geography was first systematically studied by the ancient Greeks, who also developed a philosophy of geography; Thales of Miletus, Herodotus, Eratosthenes, Aristotle, Strabo, and Ptolemy made major contributions to geography. The Roman contribution to geography was in the exploration and mapping of previously unknown lands. Greek geographic learning was maintained and enhanced by the Arabs during the Middle Ages. Arab geographers, among whom Idrisi, Ibn Battutah, and Ibn Khaldun are prominent, traveled extensively for the purpose of increasing their knowledge of the world. The journeys of Marco Polo in the latter part of the Middle Ages began the revival of geographic interest outside the Muslim world.
With the Renaissance in Europe came the desire to explore unknown parts of the world that led to the voyages of exploration and to the great discoveries. However, it was mercantile interest rather than a genuine search for knowledge that spurred these endeavors. The 16th and 17th cent. reintroduced sound theoretical geography in the form of textbooks (the Geographia generalis of Bernhardus Varenius) and maps (Gerardus Mercator's world map). In the 18th cent. geography began to achieve recognition as a discipline and was taught for the first time at the university level.
The modern period of geography began toward the end of the 18th cent. with the works of Alexander von Humboldt and Karl Ritter. Thenceforth two principal methods of approach to geography can be distinguished: the systematic, following Humboldt, and the regional, following Ritter. Of the national schools of geography that developed, the German and the French schools were the most influential. The German school, which dealt mainly with physical geography, developed a scientific and analytical style of writing. The French school became known for its descriptive regional monographs presented in a lucid and flowing manner; human and historical geography were its forte. Although emphasis has shifted several times between the approaches and viewpoints, their interdependence is recognized by all geographers.
Since the end of World War II, geography, like other disciplines, has experienced the explosion of knowledge brought on by the new tools of modern technology for the acquisition and manipulation of data; these include aerial photography, remote sensors (including infrared and satellite photography), and the computer (for quantitative analysis and mapping). The quantitative method of geographical research has gained much ground since the 1950s, Edward Ullman and William Garrison of the United States and Peter Haggett of Great Britain being leading exponents.
Important contributions to the advancement of geography and to the development of geographic concepts have been made by Ferdinand von Richthofen, Albrecht Penck, Friedrich Ratzel, Alfred Hettner, Karl Haushofer, and Walter Christaller in Germany; Paul Vidal de la Blache, Jean Brunhes, Conrad Malte-Brun, Elisée Reclus, and Emmanuel de Martonne in France; and William Morris Davis, Isaiah Bowman, Ellen Churchill Semple, Carl O. Sauer, Albert Brigham, and Richard Hartshorne in the United States. Today geography is studied by governmental agencies and in many of the world's universities. Research is stimulated by such noted geographic institutions as the Royal Geographical Society (1830, Great Britain), the American Geographical Society (1852, United States), and the Société de Geographie (1821, France).