What was the Indus Valley civilization, and why did it take until the 1920s to discover its significance?

 It was larger than ancient Egypt and Mesopotamia combined. Yet this massive Bronze Age empire vanished so completely that humanity forgot it existed for 3,000 years.

Spanning what is now Pakistan and northwestern India, the Indus Valley Civilization built some of the ancient world's most sophisticated cities, such as Harappa and Mohenjo-Daro. These cities featured grid-planned streets, standardized weights and measures, multi-story brick houses, and indoor plumbing with complex drainage systems that rivaled those of ancient Rome. However, despite this immense scale and technological advancement, the ruins were not properly recognized as a distinct, highly ancient civilization until the 1920s.

There are several reasons why this massive society stayed hidden in plain sight for so long:

• No colossal stone monuments: Unlike the Egyptians with their massive stone pyramids or the Mesopotamians with their towering ziggurats, the Indus people built primarily with baked clay bricks. Over millennia, the shifting courses and seasonal floods of the Indus River buried these brick cities under deep layers of alluvial silt.
• Industrial destruction: When engineers were building the Lahore-Multan railway in the 1850s, they stumbled upon massive mounds of ancient, perfectly fired bricks. Unaware of their immense historical value, workers used millions of these 4,000-year-old bricks as track ballast, completely destroying vast sections of the Harappan ruins before archaeologists ever saw them.
• Historical silence: The Indus script remains undeciphered today. Without readable texts, and with no clear mentions in the surviving records of other well-documented contemporary civilizations, the Indus Valley left no obvious historical breadcrumbs for scholars to follow.
• Archaeological misdirection: 19th-century explorers like Charles Masson and Alexander Cunningham actually found Indus artifacts, including intricately carved steatite seals featuring unfamiliar script and animal motifs. However, because scholars at the time assumed complex society in the region began much later, these artifacts were mistakenly attributed to more recent eras or dismissed as anomalies left by foreign traders.

The breakthrough finally came in the early 1920s. Archaeologists from the Archaeological Survey of India, including Daya Ram Sahni and R.D. Banerji under the leadership of John Marshall, began systematic excavations at Harappa and Mohenjo-Daro. They uncovered distinct layers of occupation stretching far deeper into the past than anyone anticipated. When Marshall formally announced the discovery to the world in 1924, it instantly pushed the timeline of South Asian history back by thousands of years, finally bringing a forgotten urban empire back into the light.

What is the oldest civilisation that no longer exists?

 Every time you count 60 seconds in a minute, you are using math invented by a civilization that vanished over 4,000 years ago. Long before the pyramids of Egypt were conceived, the Sumerians built what historians widely consider the world's first true civilization, laying down blueprints for urban living that still echo in cities today.

Emerging in the historical region of Mesopotamia around 4500 BCE, Sumer was not a single unified empire but a collection of fiercely independent city-states, such as Uruk, Ur, and Eridu. These cities sat between the Tigris and Euphrates rivers, a volatile environment that demanded intense cooperation to master. To survive the unpredictable floods and scorching summers, the Sumerians engineered massive irrigation canals, transforming arid mudflats into highly productive agricultural centers.

This agricultural surplus allowed populations to boom and led to an explosion of innovation. The Sumerians are credited with a staggering number of historical "firsts." They invented the wheel, initially for pottery and later for transport. To manage the complex administration of their temples and grain silos, they developed cuneiform around 3200 BCE, creating the first known system of writing by pressing wedge-shaped reeds into wet clay tablets. They also gave the modern world its concept of time; their base-60 mathematical system is the direct reason a circle has 360 degrees.

Despite their brilliance, the Sumerian civilization eventually faded. The very geography that made them rich also left them vulnerable to invasion, as they lacked natural defensive borders. Over centuries of warfare, they were gradually conquered and absorbed by neighboring peoples, most notably the Akkadians under Sargon the Great around 2334 BCE.

Sumer did not collapse in a single catastrophic event. Instead, it underwent a slow cultural assimilation. By 2000 BCE, Sumerian had ceased to be a spoken language, replaced entirely by Akkadian, though Babylonian scholars continued to study it as a sacred and literary language for centuries. Today, the Sumerians are long gone, but the foundational pillars of their society—writing, law, urban planning, and mathematics—remain deeply embedded in modern human culture.

What is the great mystery associated with the Harappan civilization?

Indus Valley Civilization script is the biggest mystery of Ancient India History. Many scholars have tried to decipher the script but have been unable to come on a consensus.

The information on Indus valley civilization becomes limited due to its ambiguous script and historians have not been able to find a Rosetta stone till date so that a proper decipherment could be done.

The picture has something written on it but can't be deciphered and in it, it seems like a man is worshipping a deity of peeple tree, there is a goat nearby (probably for sacrifice) and there are seven attendants who can be considered sapt Matrikas. In another seal as well there is one goddess attended by seven goddesses and each Goddess has its own animal (probably their vahans or the animals were sacrificed to them).

The above seal shows a person (looks like a female) slaying a bull and a deity sitting in yogic posture. Either it's a scene of sacrifice to the deity or its depiction of Mahishasura Mardini.

So, the inability decipherment of Indus valley civilization seals is a huge block in understanding the core of the Civilization. But it's absolutely clear that Yoga was a huge part of Indus Valley Culture.