In Bihar from the eighth century onwards the influence of tantrism was powerful and disastrous.
It is about this time too that we hear of tantrism in Hinduism.
tantrism is a species of religious magic, differing from the Vedic sacrifices in method rather than principle.
The inference seems to be that early in the eighth century Indian Buddhists officially recognized tantrism.
On the other hand tantrism infected Buddhism soon after this period.
type of Hindu religious book, 1799, from Sanskrit tantram, literally "loom, warp," hence "groundwork, system, doctrine," from tan "to stretch, extend," from PIE root *ten- "to stretch, extend" (see tenet).