This groundbreaking book develops a new periodization for understanding contemporary international history. It challenges West-centric approaches by setting up timelines appropriate for a global approach to International Relations. --- Shifting the focus beyond great power wars, it incorporates economic, societal and environmental changes to redefine what constitutes significant historical moments for both the Global North and South. It uncovers pivotal turning points in the 1840s, 1970s and now, that highlight the formation, dominance, unravelling and replacement of the Western world order. It offers new foundations for understanding both how we arrived at where we stand today and what might lie ahead. --- About the author: Barry Buzan is Professor Emeritus at the London School of Economics and Political Science and a Fellow of the British Academy.