I believe that it was in the Babel's tower. I don't believe that only the change of language would be sufficient to disperse all people around the world. On the other hand, to see persons have their countenance and color changed together with their language would seem to be a aberration.
It appears that when GOD gave every body a different language and the Bible does not expand upon that, He dispersed people. I have not really studied it but Nimrod was the first emperor of the world and Babylon. During this time, God changed all languages and dispersed people across the world.....Was it that this was during Peleg's lifetime. We Know that the world was divided during His lifetime. Just a thought?
Blade