The province of Nuristan – land of light – in Afghanistan used to be known as Kafiristan – land of unbelievers – before the inhabitants were (forcibly) converted to Islam in 1895. They formerly practiced a Vedic religion – basically a precursor of Hinduism. The Nuristanis were among the last holdouts practicing an ancient religion in a place surrounded by Islam. The Kalash of Pakistan are still holding out and practice a similar religion. There are theories that they are descended from Alexander’s soldiers but genetic investigation says the Kalash are purely Indo-Iranian with no Greek admixture.
A great, fun, easy to read book about Nuristan is A Short Walk In The Hindu Kush by Eric Newby – check it out here.