Sindhu in might surpasses all the streams that flow. […] Like floods of rain that fall in thunder from the cloud, so Sindhu rushes on bellowing like a bull. Rigveda 10.75

Sindhu, the Indo-Iranian name for River Indus, is a Sanskrit term meaning “sea” or “ocean”.

After the split of Indo-Iranian culture into Iranian and Indo-Aryan branches around 2000 BCE, Sindhu became Hindu in Old Persian and the fertile floodplains it nourished came to be known as “Hindu Astan”, meaning “Indus land”.

The word Hindu, once simply a geographical marker, would eventually evolve into an identity and a faith. Its Greek and Latin transliterations, Indos and Indus, expanded the term’s reach, defining not just a region but an entire subcontinent.

During the time of the Achaemenids, Darius the Great is said to have commissioned the Greek explorer Scylax (among others) to sail and chart the course of the Indus. According to Herodotus, Scylax set out from a city called Caspatyrus (likely Kashmir or a misspelling of Paskapyrus [Peshawar]) and sailed downstream.

Using the intel gathered during this expedition, Darius conquered the region that lay southeast of Gandhara soon afterward, adding it to his empire as a new province called Hinduš (modern-day Sindh). The name of the province was translated by Greek historians as India, but with time, it came to refer to the lands, people, and culture of the region that lay around the Indus and the subcontinent that extended much farther eastward.

This makes Sindhu in a very real sense, the father of India. But its influence goes much further than the subcontinent’s name. Sindhu is the life-giving artery that allowed the first major civilization in the region, the Indus Valley Civilization (IVC), to flourish 5000 years ago.

Sindhu’s regular flooding cycles deposited rich silt along its banks, enabling agriculture to support large urban centers like Harappa and Mohenjo-daro, whose grid layouts, advanced drainage systems, and standardized weights & measures hint at a level of social organization that wouldn’t be seen again for millennia.

This made Sindhu an axis of cultural and economic exchange. The people of the Indus Valley were active participants in an ancient trade network that stretched across Mesopotamia, the Persian Gulf, and Central Asia.

A 24th-century BCE inscription from the Ancient Sumer, attributed to Sargon of Akkad, boasts:

“Ships from Meluhha, Magan, and Dilmun he moored at the docks of Akkad.”

Meluhha is widely believed to be the IVC, suggesting that its people were exporting goods, perhaps cotton textiles, carnelian beads, and lapis lazuli, to Mesopotamian city-states. Indus seals, featuring a still-undeciphered script, have been found as far as Mesopotamia, implying that not just trade but cultural and bureaucratic engagement took place.

The complexity of Indus society is also evidenced by its lack of monumental palaces or centralized religious structures, a rarity among early civilizations. Unlike the contemporaneous Mesopotamians or Egyptians, who left behind records exalting their kings and gods, the people of Sindhu left behind meticulously planned cities but few obvious signs of hierarchical rule.

This has led some to speculate that their political organization was either remarkably decentralized or functioned through an administrative bureaucracy that remains elusive to archaeologists.

But even great civilizations are at the mercy of nature. By 1700 BCE, the IVC had declined and most of its cities had been abandoned, possibly due to an abrupt century-long global drought that disrupted and caused the collapse of many other contemporary civilizations.

With Sindhu no longer able to sustain the same urban densities, its people migrated eastward, towards the more stable monsoon-fed Ganges basin. The same global climatic anomaly may have also been responsible for driving Indo-Aryan peoples towards South Asia, bringing new languages, rituals, and social structures. The influx of these influences gave rise to Vedic culture, an evolution of the civilization that had flourished along Sindhu’s banks.

Even as the Indo-Aryans spread eastward, they maintained a deep cultural memory of the lands they first encountered. The Vedic peoples, whose society was organized around pastoral and agrarian economies, must have found in Sindhu both a nourishing deity and an immutable landmark. This is evidenced by its reference in early Aryan hymns as a mighty force of nature.

In a way, Sindhu has always been the silent architect of the Indian subcontinent’s history, shaping the land and its people. It has watched empires rise and fall, cities emerge and vanish, kings ascend and be deposed, even gods fall in and out of favor. Yet through it all, our primordial father, Sindhu, has flowed on unchanged.