Punjab was Buddhist country for roughly eight hundred years. Taxila had major monasteries at Dharmarajika, Jaulian and Mohra Muradu. Sanghol in Fatehgarh Sahib district had a stupa with Kushan-period carved railings. Sites are scattered across both Punjabs.
Ashoka governed Taxila as a prince and his edicts at Shahbazgarhi and Mansehra are the north-western end of the series.
The Kushans under Kanishka, ruling from Peshawar, produced the Gandhara school, which invented the human image of the Buddha that east Asia inherited.
Chinese pilgrims, Faxian, Xuanzang and others, came through Punjab and left descriptions of the monasteries, which are among the best sources for the period.
It ended with the Hun incursions of the fifth and sixth centuries and the destruction of the monastic establishment, and Buddhism disappeared from Punjab so completely that it left almost nothing in the region's memory of itself.
Punjab holds one of the world's most important Buddhist archaeological landscapes and almost nobody who lives there thinks of it as part of their history.
Xuanzang counted monasteries and monks district by district in the seventh century and reported a great many of them already empty. His account is the last description of the system working and the first description of it failing, and both are in the same book.
The Sanghol pillars had been buried deliberately, stacked in a pit beside the stupa, which is why they came up whole in 1985 instead of in fragments. Somebody in antiquity took the trouble to bury a monument rather than let it be broken up, and nobody knows who, or what they were hiding it from.
The tradition ended in the plain sometime after the Huna invasions and before the Ghaznavids. There is no account of how it ended and almost no evidence of the period in which it did.