For centuries, population size defined power. More people meant more soldiers, more workers, more leverage. That rule is breaking. As birth rates collapse and societies age, power is not disappearing. It is being rebuilt on a different foundation. Automation, artificial intelligence, and autonomous systems are replacing human scale with technological capability, allowing nations to grow stronger even as their populations shrink. Power After Population explains the historic shift from demographic dominance to system dominance. It shows why large populations are becoming strategic liabilities, how shrinking nations can maintain or even expand global influence, and why future power will belong to states that substitute machines for people faster than others can adapt. This book explores how automation is reshaping military force, economic production, governance, and control. It examines the collapse of labor-based geopolitics, the rise of autonomous power structures, and the growing separation between human populations and the systems that rule them. Drawing on history, emerging technology, and global trends, it reveals why old measures of strength no longer apply and why the next global hierarchy is already forming. Written for readers who want to understand where power is actually moving, this book offers a clear, unsentimental map of the post-population world and the forces that will determine who rules it.