Les,

You are probably right. My own area of specialization is considerably later. It certainly was assumed for years that the Indo-Europeans emerged from India, simply because Sanskrit was the earliest known IE language for many years. That assumption in turn led to the assumption that many common IE cultural traits originated in India too. But later research may well have shown the premise to be as difficult to maintain as the conclusion.

One of the problems here is "how do we decide that someone is Indo-European?" If we do not have linguistic records, it's a tough case to make. This is the same problem we encounter later, in the time period I am most familiar with, in deciding that people are "Celtic" (as opposed to, say, Lepontic or Iberian).

By the way, my unfinished sentence from the post above should be:

I firmly believe that the origins of many literary ideas ascribed to others, including some English people, will someday be found in unpublished Irish folklore collections.