[3][2] Following the Achaemenid conquest of the Indus Valley, around 540 BCE, Taxila became the capital of their Hindush satrapy (colony), the earliest known archaeological remains date to this period.

[2][6][7] Taxila was at the crossroad of the main trade roads of Asia, and was probably populated by Indians, Persians, Greeks, Scythians and many ethnicities coming from the various parts of the Achaemenid Empire.

[8] According to John Marshall, Taxila emerged as a centre of learning after the Persian conquests due to its geographical position, "at the North-Western gateway of the subcontinent," and the "cosmopolitan character of her population.

[1] According to John Marshall, "In early Buddhist literature, particularly in the Jatakas, Taxila is frequently mentioned as a university centre where students could get instruction in almost any subject, religious or secular, from the Veda to mathematics and medicine, even to astrology and archery.

"[1] The role of Taxila as a center of knowledge grew stronger under the Maurya Empire and Greek rule (Indo-Greeks) in the 3rd and 2nd centuries BCE.