Chapter 1 — The Discovery
The Indus Valley civilization was unknown to modern scholarship until the 1920s. This is remarkable. Egypt had been a source of fascination for European scholars since Napoleon's expedition in 1798. Mesopotamia had been explored since the mid-nineteenth century, when Austen Henry Layard excavated the Assyrian palaces at Nimrud and Nineveh. But the Indus Valley -- a civilization contemporary with both, and larger in geographic extent than either -- was invisible. It had left no pyramids visible above the ground, no massive stone temples, no ruins that travelers could identify as the remains of a great civilization. Its cities had been buried under centuries of alluvial sediment, their bricks scavenged by later inhabitants for building material. The civilization had been so thoroughly forgotten that no historical tradition -- Hindu, Buddhist, Persian, or Greek -- preserved even a memory of its existence.
The first clues emerged in the 1850s, when British engineers building a railway line through the Punjab province of what was then British India discovered large quantities of well-made fired bricks at a mound near the town of Harappa (hah-RAH-pah), in present-day Pakistani Punjab. The bricks were uniform in size, high in quality, and available in enormous quantities. The engineers used them as ballast for the railway track -- destroying, in the process, an unknown amount of one of the world's oldest cities. Alexander Cunningham, the first director of the Archaeological Survey of India, visited the site in 1872-1873 and noted the bricks and some carved artifacts, including a small stone seal bearing an image of a bull and several mysterious signs. Cunningham did not realize what he was looking at. He assumed the remains were relatively recent -- perhaps medieval.
The breakthrough came in the early 1920s. Rai Bahadur Daya Ram Sahni (DYE-ah RAHM SAH-nee) began systematic excavations at Harappa in 1921. In the same year, Rakhal Das Banerji (rah-KAHL DAHS bah-NER-jee) began excavating a mound called Mohenjo-daro (moh-HEN-joh DAH-roh), meaning "Mound of the Dead" in Sindhi, located roughly 570 kilometers to the southwest in the Sindh province of present-day Pakistan. At both sites, the excavators found the same thing: the remains of large, carefully planned cities, built with standardized bricks, equipped with elaborate drainage systems, and containing artifacts -- pottery, stone tools, jewelry, and small stone seals with carved images and inscriptions -- that belonged to no known civilization.
Map of the Indus Valley civilization showing Harappa, Mohenjo-daro, and major sites
John Marshall, the director-general of the Archaeological Survey of India, recognized the significance of the finds. In a 1924 announcement in the Illustrated London News, Marshall declared the discovery of a previously unknown civilization, contemporary with ancient Egypt and Mesopotamia. The announcement was a sensation. A third great civilization of the Bronze Age, unknown to history, had been hiding in plain sight in the floodplains of the Indus River.
Subsequent decades of excavation expanded the known extent of the civilization dramatically. The Indus Valley civilization -- also called the Harappan civilization, after its first excavated site -- was not confined to the Indus Valley. Sites were found across an enormous area: from Sutkagen Dor (soot-KAH-gen DOR) on the coast of Balochistan (near the modern Iranian border) in the west, to Alamgirpur (AH-lahm-geer-poor) near Delhi in the east; from Shortugai (SHOR-too-guy) in northern Afghanistan in the north, to Daimabad (DYE-mah-bahd) in Maharashtra in the south. The civilization's territory covered approximately 1.5 million square kilometers -- larger than ancient Egypt and Mesopotamia combined. Over 1,500 sites have been identified, ranging from large cities (Harappa, Mohenjo-daro, Dholavira, Rakhigarhi) to small villages and seasonal camps.
The population at the civilization's peak, roughly 2600-1900 BCE, has been estimated at up to five million people -- a figure comparable to the contemporary populations of Egypt and Mesopotamia. The Indus civilization was, by any measure, one of the major civilizations of the ancient world. That it remained unknown until the twentieth century is a reminder of how much of human history lies hidden beneath the surface of the Earth.