As mentioned in an earlier lecture, Tantra was clearly present in India from the 5th century CE on.
But long before that time, some aspects of Tantra were already pervasive in Indian religion.
For example, mother goddesses in villages had already been around for many centuries (and even before the arrival of the Aryans and the Sanskrit language). Inasmuch as goddesses are central to much of Tantra, this tradition actually has a long history.