Given how the story of of Siddharth Gautama / Buddha was Christianized to become the story of Barlaam and Josaphat (http://en.wikipedia.org/wiki/Barlaam_and_Josaphat), how could a hypothetical Christianized branch of Buddhism or a Buddhaized / Dharmic form of Christianity come into being and dominate Central Asia along with much of what is today Afghanistan / Pakistan up to the modern era?