The remarkable spatial correspondences--at several scales--of “great ancient civilizations” with the tectonic activity at plate boundaries is examined from five independent viewpoints. All are consistent with direct cultural influence of active tectonism (locally including volcanism) in promoting cultural complexity. Tectonism seems to have functioned as a cultural stimulant; “tectonic cultures” were systematically more dynamic than those of tectonically quiescent cultures. The forced pace of change along active tectonic zones apparently produced an acceptance of innovations introduced by trade with more-complex cultures. Thus tectonism may behave more like a cultural variable than a conventional environmental variable. Though the modern world submerges its evidence among other concerns, vestiges of the ancient relation show through.