Unicorn seal with its impression. This was one of the very first seals discovered in recent times. Published in 1912, it played a role in encouraging Marshall to excavate in 1921. It is currently held by the British Museum in London.
He also notes that historians of Alexander reported a comparable desiccation in the 4th century BC. Could this have occurred during the preceding millennium, after the Indus civilisation? As part of the evidence for possibly higher rainfall in the third millennium BC, Marshall observed that Mohenjo-daro’s builders used kilnfired, and hence more durable, bricks rather than more friable, but much cheaper, sun-dried bricks. Furthermore, some of the animals frequently depicted on the Indus seals, such as the tiger, rhinoceros, and elephant, which are not found in the region today, are commonly found in damp, jungly country, unlike the lion, which prefers the dry zone and is not depicted on the seals. Yet Marshall concluded that none of his evidence was decisive. Kiln-fired bricks may simply have asserted the importance of certain excavated buildings or been a symbol of luxury, while the disappearance of the tiger from Sindh occurred as recently as the late 19th century (partly as a result of a reduction in its habitat by increased animal grazing and the effects of big-game hunting). Opinion on Indus climate change remains divided today, after several inconclusive studies. Another late 19th-century change to the southern Indus valley was the gradual introduction of artificial control of the river with embankments and dams and the construction of extensive irrigation canals. These helped farmers, but not archaeologists. Within decades the over-irrigated land, including the ruins of Mohenjo-daro, now no longer washed by annual Indus floods, became impregnated with salts commonly known as saltpetre. The slightest rainfall would convert the anhydrous salt into the hydrous form, whitening the landscape with ‘a brittle shining crust that crushes beneath the step like a satanic mockery of snow’, noted archaeologist Stuart Piggott at Mohenjo-daro in the 1940s. The salination was accompanied by a more
The Past | April/May 2021