As Europe disappears, Eurasia coheres. The supercontinent is becoming one fluid, comprehensible unit of trade and conflict as the Westphalian system of states weakens and older, imperial legacies – Russian, Chinese, Iranian, Turkish – become paramount. Every crisis from Central Europe to the ethnic-Han Chinese heartland is now interlinked. There is one singular battlespace. CNAS Senior Fellow Robert D. Kaplan provides a historical and geographical guide to it.