5000 to 7000 BC. Early-Neolithic deformed skull from Iran, Wikipedia image: these skulls are common from about 5000 to 7000 BC in the areas that would later become Iran and then diffusing out into the surrounding territories. Many skulls in the same time period from Iraq, Southern Turkey and Syria are also deformed but not usually so severely. In later historical time many of the Iranian-speaking nomads of Central Asia continued the tradition and eventually the trait was introduced into Europe from the East by the invasions of the Huns.

http://frontiers-of-anthropology.blogspot.com/2011/04/more-on-coneheads.html