Tantra's Dark Period
Somewhere around the eighth century, Tantric practitioners were forced to go “underground” and practice their beliefs covertly, because Tantra was viewed as strange and perhaps connected to black magic. The sex rituals commonly associated with Tantra were also viewed as highly controversial during this time.
During a drawn-out period usually assumed to have been between the seventh and twelfth centuries, Muslims invaded India and enacted laws prohibiting many popular beliefs. Anyone caught following Tantric beliefs or practices could be executed during this period.
As a result of these and other occurrences, Tantric followers in India and other regions were forced to be very secretive about their actions for several centuries.
What are left-handed and right-handed Tantras?
In some older writings about Tantra, believers are divided into two groups — left-handed and right-handed — based on the path the person took in following the Tantric teachings. Left-handed Tantras were the ones who regularly indulged in sensory pleasures and “vices,” such as alcohol, meat, and sex, and incorporated these pleasures into their rituals. Right-handed Tantras had more self-control and were generally viewed to be more spiritually pure and disciplined. Right-handed Tantra did not include sexual acts.