"By the time that the Turko-Islamic conquerors arrived in North India, in the eleventh to thirteenth centuries, Buddhism was no longer a religion of a floating population of itinerant monks but had become institutionalized in monasteries, which, supported by royal endowments of land as well as by donations from the mercantile communities, tended to become large academically oriented centres with permanent residents, vulnerable to outside attack, but still aloof from the rural masses (which only adopted random cultic elements from the religion). What happened, then, during the Islamic conquest, is that the academic (and soteriological / philosophical) tradition of Buddhism was uprooted in India itself, but replaced, outside the orbit of Muslim rule, by a variety of regional forms of Buddhism."