At the beginning of the twentieth century, a European-dominated global political order existed, which also included the United States, Russia, and Japan. Over the course of the century, peoples and states around the world challenged this order in ways that sought to redistribute power within the existing order and to restructure empires, while those peoples and states in power attempted to maintain the status quo. Other peoples and states sought to overturn the political order itself. These challenges to, and the attempts to maintain, the political order manifested themselves in an unprecedented level of conflict with high human casualties. In the context of these conflicts, many regimes in both older and newer states struggled with maintaining political stability and were challenged by internal and external factors, including ethnic and religious conflicts, secessionist movements, territorial partitions, economic dependency, and the legacies of colonialism.