A section from the journey
How We Date the Cities
We cannot read the Indus writing, so we cannot ask the people their dates. Instead, scholars dig down through the layers of earth and use a tool called radiocarbon dating to measure the age of old wood, bone, and grain. From this they sketch three great stages: an early phase, the grand city phase, and a long fading. The dates are good, but they carry honest "about" around them.
Here is a fair question to ask of any old thing. How do we know how old it is? With the Indus cities, the question bites harder than usual. Their people did leave writing, but we cannot read a word of it yet. So we cannot simply open a book and find a date. We must let the earth itself tell us.
The first teacher is the ground. When scholars dig down into an old mound, they pass through layers, one beneath another. And the rule is simple and steady: the deeper you go, the older it is. Each layer is like a page laid down in its turn. The bottom page was written first.
The second teacher is a wonderful tool with a long name: . Let us understand it gently, for it is not hard. Every living thing — every tree, every cow, every grain of wheat — takes in a special, faint form of carbon while it is alive. When it dies, no more comes in, and the carbon already inside slowly fades away at a steady, known speed.
So here is the trick. If you find an old charred beam, or a burnt seed, or a piece of bone in a dig, you can measure how much of that special carbon is left. The less there is, the longer ago the thing died. It is like reading a slow clock that began ticking at the moment of death. From this, science can say, with care, how old something is.
Put the layers and the clock together, gather thousands of tests across many sites, and a clear shape appears. Scholars draw the civilization in three great stages, like the morning, noon, and evening of a long day.
The first stage they call the Early Harappan, from about 3300 to 2600 BCE. This was the slow gathering: villages growing, crafts sharpening, towns beginning to take shape. The great cities were not built yet, but the seeds were being sown.
The second stage is the Mature Harappan, from about 2600 to 1900 BCE. This is the noon of the day, the grand age of the great planned cities, with their straight streets and clean drains and far-reaching trade. When people speak of the wonder of this civilization, this is most often the time they mean.
The third stage is the Late Harappan, from about 1900 to 1300 BCE. This is the long evening: the big cities slowly emptying, the people scattering into smaller villages and drifting eastward. We will come to why this happened, gently, near the end of our era. For now, simply hold the shape: a rise, a height, and a fading.
One last thing, and it matters most of all. Notice the little word "about" that sits before every date. Real science does not pretend to a sharpness it does not have. The seams between the stages may be off by a hundred years either way. A good scholar, like a good teacher, says plainly what is known and admits freely what is not. That honesty is not a weakness. It is the very strength of the method.
It can feel safer to claim we know a thing exactly than to say "about, roughly, as best we can tell." Yet the honest answer is often the wiser one. Where in your own learning might it be braver to say "I am not quite sure" than to pretend to be certain?
How can we put a date on a city whose people left no readable books? This is a fair question, and the honest answer is a small lesson in how history is built. First, the earth keeps order. The deepest layer of a dig is the oldest, and each layer above is younger, like pages stacked in time. Second, there is a marvellous tool called radiocarbon dating. Every living thing takes in a faint, special form of carbon while it lives, and this slowly fades after death at a steady, known rate. By measuring how much is left in an old seed, a charred timber, or a bone, scientists can tell roughly how long ago it died. From thousands of such tests, scholars sketch the civilization in three great stages. The Early Harappan was the slow gathering, around 3300 to 2600 BCE. The Mature Harappan was the age of the grand planned cities, around 2600 to 1900 BCE. The Late Harappan was the long fading and scattering, around 1900 to 1300 BCE. Each date carries an honest "about," for science states what it knows and admits what it does not.
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