New Radiocarbon Dates Push Mohenjo-daro Back to 3300 BC- Rivaling the Earliest Cities of Egypt and Mesopotamia

A city long celebrated as one of the great urban centers of the ancient world is now proving to be even older—and more complex—than previously believed. New excavations at Mohenjo-daro, the iconic Indus Valley site in present-day Pakistan, have pushed its urban roots back several centuries, reshaping how archaeologists understand the rise of early cities in South Asia.

Located along the Indus River in Sindh’s Larkana district, Mohenjo-daro spreads across more than 620 acres. At its height, it supported a population estimated at up to 40,000 people, placing it among the largest cities of the Bronze Age—comparable in scale to urban centers in ancient Egypt and Mesopotamia. But until recently, its earliest phases remained less clearly defined.

A City Older Than the “Mature” Harappan World

Fresh radiocarbon dating from excavations conducted in 2025–2026 now confirms that Mohenjo-daro was already occupied during the Early Harappan (Kot Diji) Phase, between roughly 3300 and 2600 BC—well before the emergence of the so-called Mature Harappan urban system.

This is not a minor chronological adjustment. It suggests that urban development in the Indus Valley was more gradual and deeply rooted than the traditional narrative of a sudden rise around 2600 BC.

The excavation, carried out by a joint Pakistani and international team led by Dr. Asma Ibrahim, Ali Lashari, and Dr. Jonathan Mark Kenoyer, focused on the area west of the site’s famous Stupa Mound, according to reporting by Dawn. There, archaeologists revisited a massive mudbrick structure first uncovered in 1950 by Sir Mortimer Wheeler.

Wheeler had interpreted the feature as a flood-control embankment. The new work tells a different story.

Rewriting the Function of the City Wall

Detailed stratigraphic analysis and radiocarbon dating of five new samples demonstrate that this structure was not simply defensive or hydraulic infrastructure. Instead, it appears to be a multi-phase mudbrick city wall, constructed and expanded over centuries.

Crucially, pottery and carbon samples from the lowest levels indicate that the earliest phase of the wall dates to around 2700–2600 BC, at the very end of the Early Harappan period—approximately a century before the classic urban phase began.

Even more revealing is what lies beneath.

Deep coring below the wall uncovered Kot Diji–style pottery, confirming the presence of a substantial settlement predating the wall itself. In other words, Mohenjo-daro was not built from scratch during the Mature Harappan phase; it evolved from an already established community.

This aligns with parallel findings at Harappa, another major Indus city, where early fortifications and occupation layers date to a similar timeframe.

Layers of Urban Evolution

The upper levels of the wall tell a second part of the story. Radiocarbon dates and material culture show that later construction phases belong firmly to the Mature Harappan period (after 2600 BC), when the city reached its architectural and social peak.

The wall was not static. It was expanded, reinforced, and maintained until at least 2200 BC, and possibly longer. This long-term investment suggests a sophisticated understanding of urban planning and resource management.

Future excavations aim to trace the full circuit of the wall around the Stupa Mound, with particular attention to locating gateways—key features that could clarify how movement, trade, and security were organized within the city.

Beyond the Wall: A Broader Archaeological Landscape

While the new findings focus on early urban phases, Mohenjo-daro continues to yield discoveries from much later periods as well. In 2023, excavations near the Stupa area uncovered hundreds of Kushan-era coins, dating between the 2nd and 5th centuries AD.

Weighing approximately 5.5 kilograms in total, the coins were fused together by centuries of heat and pressure, making precise counts difficult. Their presence highlights the site’s long-term significance as a place of activity, reuse, and memory, long after the Indus Civilization itself had declined.

Earlier excavations in the 1920s and 1930s had already revealed thousands of coins and artifacts, many of which are now dispersed across museum collections in South Asia and beyond.

Why Mohenjo-daro Still Matters

What makes Mohenjo-daro extraordinary is not just its age, but its level of urban sophistication. The city is famous for its standardized baked bricks, carefully planned streets, advanced drainage systems, and monumental structures such as the Great Bath—often interpreted as having ritual or civic significance.

Yet one of its most enduring mysteries remains unsolved: the Indus script, found on seals and tablets across the site, has never been definitively deciphered. Without readable texts, archaeologists must reconstruct the city’s history through architecture, artifacts, and increasingly, scientific methods like radiocarbon dating.

The new evidence adds a critical piece to that puzzle. It shows that Mohenjo-daro was not simply a product of a mature civilization—it was part of a longer, experimental process of urban formation, stretching back into the Early Harappan world.

A Turning Point in Indus Valley Research

Archaeologists involved in the project describe the findings as a significant step forward in understanding the evolution of urban life in the Indus Valley. Rather than a sudden emergence of cities, the evidence now points to a multi-phase trajectory, where early communities gradually developed the social, economic, and architectural systems that would define one of the world’s earliest civilizations.

That shift in perspective matters. It places Mohenjo-daro not just as a peak achievement, but as a living laboratory of early urbanism, where ideas about planning, infrastructure, and social organization were tested and refined over centuries.

And as new excavations continue—probing deeper layers, mapping hidden structures, and applying more precise dating techniques—the city is likely to keep rewriting its own story.

Cover Image Credit: Saqib Qayyum – Public Domain