These principles make it possible to pinpoint the locus in space more or less accurately even for a language family as old as IE. Here it will be sho… - Johanna Nichols

The location of the Anatolian branch of IE (Hittite and its sisters) is a problem, or at least a puzzle, for IE homeland studies. The Anatolian languages are attested very early in Asia Minor, removed from Europe and far from the steppe; Gamkrelidze and Ivanov ... offer as a strength the ability of their proposed homelands to account for the location of Hittite with minimal migration. Alternatively or additionally, the location of Tocharian—attested in the early centuries AD well to the east of most IE territory in present-day Xinkiang (Chinese Turkestan)—is a problem or a puzzle... Accounting for the locations of both Hittite and Tocharian is usually presented, at least rhetorically, as a major problem.

Approximately every two millennia, then, there has occurred a spread of a language family from a locus in the eastern part of the central Eurasian spread zone to cover the steppe and central Asia, extending partially or intermittently to the Danube plain, Anatolia, and northern Mesopotamia. The loci of the historically attested spreads are near the edge of the spread zone rather than in the centre of it: the piedmont to the south (Bactria-Sogdiana) for Iranian, the north of Mongolia for Turkic and Mongolian. The trajectories of language spread run east to west along the steppe and through the desert to the Near East as shown .... To take clear and historically well-attested examples, the locus, trajectories, and range of IE must have been much like those of Iranian or Turkic. ... The placement of the locus specifically in the vicinity of Bactria-Sogdiana is justified in .... A homeland reconstructed as locus, trajectory and range removes the dilemma: a locus in the vicinity of Bactria-Sogdiana implies a spread beginning at the frontier of ancient Near Eastern civilization and a range throughout the steppe and central Asia, following the east-to-west trajectory, with occasional or periodic spreads into the Danube plain and Anatolia.

No migrations are required to derive the attested IE distribution from a reconstructed homeland consisting of a locus in western central Asia and a range over the steppe and desert. Sometime in the fourth to early third millennium, PIE spread along the steppe and southern trajectories to occupy the entire reconstructed range: the steppe, the desert of wester central Asia, part of the adjacent mountains, and perhaps some of south- west Asia. At this time its distribution was continuous, and that distribution had been achieved not by migration but by expansion.