Imagine that we were to discover an ancient Keltic tribe living in three isolated valleys up in the Alps.
Imagine that, through all the intervening centuries of the Great Interruption, they had, nonetheless, somehow managed to hold on to their Old Religion.
Amazingly enough—specifics aside—this not an imaginary scenario.
As the Indo-European-speaking peoples first entered the Indian subcontinent, groups broke off the main migration and settled along the way.
That's how the Kalasha, the last surviving pagans of the Hindu Kush, came to live in three isolated mountain valleys in what is now NW Pakistan.
Their religion, practiced continuously since antiquity, strongly resembles the religion of the Rig Veda, modern Hinduism's oldest scripture; some of the gods are even the same.
Alone among the Indo-European peoples, the religion of the Kalasha has never been subsumed by one of the Big Name religions. This small tribe of 4000-some people is as close as we will ever come to touching the old paganisms of the European ancestors.
As such, they have much to teach us.