According to the Silk Road philologist, Christopher I. Beckwith, the ancient Greek philosopher, Pyrrho, based his new philosophy, Pyrrhonism, on elements of Early Buddhism, most particularly the Buddhist three marks of existence. Pyrrho accompanied Alexander the Great on his Indian campaign, spending about 18 months in Taxila studying Indian philosophy. Diogenes Laërtius' biography of Pyrrho reports that Pyrrho based his philosophy on what he learned there: