Decolonizing the Math Books: The Case for Āryabhaṭa’s π

A 1930 paper dismantled every argument for Greek origin of Āryabhaṭa's discovery.

Photo by Morgan Bea on Unsplash

In the fifth century CE, two astronomers on opposite ends of Asia independently calculated accurate values of \pi. In China, Tsu Ch’ung-chih (born 430 CE) computed the ratio as 355/113. In India, Āryabhaṭa (born 476 CE) calculated it via the fraction 62832/20000, which equals 3.1416. Both breakthroughs were extraordinary mathematical achievements for their time, executed when Europe was entering its early medieval intellectual lull.

Yet, history treated them with a stark double standard.

Tsu’s discovery has never been seriously disputed; it is accepted as Chinese without controversy. Āryabhaṭa’s discovery, however, became an intellectual battleground. For over a century, Eurocentric scholars questioned whether he actually originated the value, attempting to attribute it to a Greek source, an earlier text, or a tenth-century mathematician who shared his name. This discrepancy stems from a persistent historical framework: the myth of the “Greek Miracle,” which treats ancient Greece as the independent origin point of all foundational knowledge, viewing non-Western discoveries with default suspicion.

The systematic attempt to strip Āryabhaṭa of his achievement—led by British scholar G.R. Kaye—was dismantled in a 1930 paper by mathematician Sāradākānta Ganguli in the American Mathematical Monthly. Kaye’s three primary arguments, and Ganguli’s refutations, expose the flaws in these Eurocentric assumptions.

• The “Myriad” Coincidence: Critics argued that because Āryabhaṭa’s calculation relied on a numerical base of 10,000—equivalent to the Greek myriad—he must have borrowed the concept from Greece. Ganguli proved that Āryabhaṭa used the Sanskrit unit ayuta. This magnitude is native to Indian mathematics, and the term was used in Vedic literature long before Greek civilization existed. The parallel is a numerical coincidence, not a borrowing.

• The Pulisa Chronology: Scholars cited the medieval writer Alberuni, who noted that an earlier mathematician named Pulisa used the exact same value of \pi. If Pulisa came first, they argued, the value was not Āryabhaṭa’s. Ganguli showed that Alberuni was not referencing the author of the ancient Pulisa-siddhanta, but a later, medieval recast of the work that had been updated using Āryabhaṭa’s own calculations.

• The Alexandrian Transmission: The final argument claimed that the value 3.1416 was known in Alexandria and leaked into India via trade routes. Ganguli responded with direct mathematics: Ptolemy’s Alexandrian value for \pi, expressed in degrees, minutes, and seconds, equals 3.1417. Āryabhaṭa’s value was 3.1416. The Alexandrians could not transmit a precise value they did not possess.

“The existence of contact between Greece and India cannot prove a one-way knowledge transfer, particularly for a result the Greeks did not demonstrably possess.”

— Sāradākānta Ganguli, 1930

Underlying these arguments is a refusal to accept that ancient global networks were bidirectional. Historians acknowledge an “Indosphere” where Indian philosophy, mathematics, and the decimal system radiated eastward into China and Southeast Asia. But when knowledge flows toward the West, the narrative locks up, reverting to a rigid model of Western output and Eastern input. As historian William Dalrymple notes in The Golden Road, from 250 BCE to 1200 CE, India was a confident exporter of its civilization, creating an empire of ideas based on cultural allure and intellectual sophistication. In science, astronomy, and mathematics, India taught the Arab world, which in turn transmitted that knowledge to Mediterranean Europe.

If intellectual concepts moved West, physical trade paved the way. The trading networks of the ancient world were vast and bidirectional, leaving a clear archaeological record that shatters the premise of Indian isolation. Lime plaster fragments found in Dhuwelia, Jordan, dated to approximately 4000 BCE, contained cotton fibers traceable exclusively to Baluchistan. Sometime after 2334 BCE, Sargon of Akkad recorded Indian merchant ships docked in his Mesopotamian harbor. By 2000 BCE, Indian humped zebu cattle reached the Horn of Africa, integrating into local agriculture. Even the great Egyptian Pharaoh Ramses II went to his grave in 1224 BCE with Malabar peppercorns from Kerala stuffed into his nostrils during mummification.

This interaction was institutionalized over centuries. Archaeological evidence proves a permanent Indus merchant colony existed in ancient Mesopotamia. Centuries later, these deep geopolitical ties remained unbroken: when Roman armies closed in on Alexandria, Cleopatra’s immediate instinct was to send her son to India for safety across the Red Sea trade routes.

When the exchange of goods, textiles, and livestock was explicitly bidirectional, assuming that the exchange of ideas was strictly one-way is illogical. It requires a profound leap of faith to believe that ancient merchants traded physical commodities back and forth for thousands of years, but that mathematical insights only ever traveled east. The assumption that knowledge transfer was strictly one-way requires a level of justification it has never received.

The double standard remains a blemish on historiography. When a Chinese scholar discovers something, it is recognized as Chinese. When an Indian scholar achieves the same milestone, the default instinct is to ask where he got it from. Ganguli settled the mathematical debate regarding \pi nearly a century ago, but the historiographical lesson remains vital: interaction is not the same as debt, trade is not a synonym for dependence.

Reference:

• Gānguli, S. (1930). The Elder Āryabhaṭa’s Value of π. The American Mathematical Monthly, 37(1), 16–22. https://doi.org/10.2307/2299981