The concept of geography is present in all cultures; therefore, the history of the discipline is a series of competing narratives, with concepts emerging at various points across space and time. The oldest known
world maps date back to
ancient Babylon from the 9th century BC. The best known
Babylonian world map, however, is the
Imago Mundi of 600 BC. The map as reconstructed by
Eckhard Unger shows
Babylon on the
Euphrates, surrounded by a circular landmass showing
Assyria,
Urartu, and several cities, in turn surrounded by a "bitter river" (
Oceanus), with seven islands arranged around it so as to form a seven-pointed star. The accompanying text mentions seven outer regions beyond the encircling ocean. The descriptions of five of them have survived. In contrast to the
Imago Mundi, an earlier Babylonian
world map dating back to the 9th century BC depicted Babylon as being further north from the center of the world, though it is not certain what that center was supposed to represent. Anaximander is credited with the invention of the
gnomon, the simple, yet efficient Greek instrument that allowed the early measurement of
latitude. The first rigorous system of
latitude and longitude lines is credited to
Hipparchus. He employed a
sexagesimal system that was derived from
Babylonian mathematics. The meridians were subdivided into 360°, with each degree further subdivided into 60 (
minutes). To measure longitude at different locations on Earth, he suggested using eclipses to determine the time difference between them. The extensive mapping by the
Romans as they explored new lands would later provide a high level of information for
Ptolemy to construct detailed
atlases. He extended the work of
Hipparchus, using a grid system on his maps and adopting a degree length of 56.5 miles. From the 3rd century onwards,
Chinese methods of geographical study and the writing of geographical literature became much more comprehensive than those found in Europe at the time (until the 13th century). Chinese geographers such as
Liu An,
Pei Xiu,
Jia Dan,
Shen Kuo,
Fan Chengda,
Zhou Daguan, and
Xu Xiake wrote important treatises, yet by the 17th century advanced ideas and methods of Western-style geography were adopted in China. , reconstituted from
Ptolemy's
Geographia, written During the
Middle Ages, the
fall of the Roman empire led to a shift in the evolution of geography from Europe to the
Islamic world.
Abū Zayd al-Balkhī, originally from
Balkh, founded the "Balkhī school" of terrestrial mapping in
Baghdad. Suhrāb, a late tenth century Muslim geographer accompanied a book of geographical coordinates, with instructions for making a rectangular world map with
equirectangular projection or cylindrical equidistant projection.
Abu Rayhan Biruni (976–1048) first described a polar equi-
azimuthal equidistant projection of the
celestial sphere. He was regarded as the most skilled when it came to mapping cities and measuring the distances between them, which he did for many cities in the Middle East and the
Indian subcontinent. He often combined astronomical readings and mathematical equations to develop methods of pinpointing locations by recording degrees of
latitude and
longitude. He also developed similar techniques for measuring the heights of mountains, the depths of the
valleys, and the expanse of the
horizon. He also discussed
human geography and the
planetary habitability of the Earth. He also calculated the
latitude of Kath,
Khwarezm, using the maximum altitude of the Sun, and solved a complex
geodesic equation to accurately compute the
Earth's circumference, which was close to modern values of the Earth's circumference. His estimate of 6,339.9 km for the
Earth radius was only 16.8 km less than the modern value of 6,356.7 km. In contrast to his predecessors, who measured the Earth's circumference by sighting the Sun simultaneously from two different locations,
al-Biruni developed a new method of using
trigonometric calculations based on the angle between a
plain and mountain top, which yielded more accurate measurements of the Earth's circumference, and made it possible for it to be measured by a single person from a single location. '' The European
Age of Discovery during the 16th and 17th centuries, where many new lands were discovered, and accounts by European explorers such as
Christopher Columbus,
Marco Polo, and
James Cook revived a desire for both accurate geographic detail and more solid theoretical foundations in Europe. In 1650, the first edition of the
Geographia Generalis was published by
Bernhardus Varenius, which was later edited and republished by others, including
Isaac Newton. This textbook sought to integrate new scientific discoveries and principles into classical geography and approach the discipline like the other sciences emerging, and is seen by some as the division between ancient and modern geography in the West. The influence of
Immanuel Kant,
Alexander von Humboldt,
Carl Ritter, and
Paul Vidal de la Blache can be seen as a major turning point in geography from philosophy to an academic subject. Geographers such as
Richard Hartshorne and
Joseph Kerski have regarded both Humboldt and Ritter as the founders of modern geography, as Humboldt and Ritter were the first to establish geography as an independent scientific discipline. Over the past two centuries, advancements in computer technology have led to the development of
geomatics and to the incorporation of new practices, such as participant observation and geostatistics, into geography's portfolio of tools. In the West during the 20th century, the discipline of geography went through four major phases:
environmental determinism,
regional geography, the
quantitative revolution, and
critical geography. The strong interdisciplinary links between geography and the sciences of geology and
botany, as well as economics, sociology, and
demographics, have also grown greatly, especially as a result of
earth system science that seeks to understand the world in a holistic view. New concepts and philosophies have emerged from the rapid advances in computing, quantitative methods, and interdisciplinary approaches. The 1962 book
Theoretical Geography by
William Bunge, which argued for a
nomothetic approach to geography and that from a purely spatial perspective there was no real difference between human and physical geography, has been described by
Kevin R. Cox as "perhaps the seminal text of the spatial-quantitative revolution." In 1970,
Waldo Tobler proposed the
first law of geography, "everything is related to everything else, but near things are more related than distant things." This law summarizes the first assumption geographers make about the world. == Related fields ==