Essentially, he proposes that the parent of all Indo-European languages was itself born in central Anatolia, whence it spread eastward, westward, and northward, being modified by the influences of the languages with which it came into contact, till it ultimately emerged in its recognizable, modern manifestations which we categorize into Germanic, Hellenic, Italic, Indo-Iranian, Anatolian, Armenian, Celtic, Tocharian, Albanian, and BaltoSlavic.
The intersection of various cultures affected the primordial language, shaping and mutating it into modern-day equivalents.