In an account of Eurasian regional formation that stretches back long before the nation-state, this book refutes the notion that stable regions are the luxury of prosperous, stable, democratic states. It examines case studies from regions once on the fringes of the Habsburg, Ottoman, and Russian Empires to find the often-overlooked patterns of bonding and bridging, or clustering and isolation of political power and social resources, that are associated with regional resilience or fracture in those regions today. With comparative examples from Latin America and Africa, The Neighborhood Effect offers a new explanation for the conflicts we are likely to see emerge as the unipolar US-led order dissolves, making the fractures in regional neighborhoods painfully evident.