Warfare and the military were at the center of the imperial Chinese state, though their significance was downplayed by government officials and the literati. Chinese dynasties fielded armies organized and supported by the central government that combined infantry and cavalry forces, and mixed part-time (militia) and professional soldiers. Cavalry and infantry forces were strongly, though not exclusively, connected to ethnic background. The best and most numerous cavalry came from steppe groups, and the best and most numerous infantry were Chinese. The stirrup and guns were invented in China, changing the course of both Chinese and world military history. China also had a highly developed tradition of military thought that drew upon a classical tradition and was vastly elaborated and expanded upon during the imperial period. What most distinguished imperial China from its earlier period was the effective use of war to create and support a unified state. Overall, the history of warfare and the military in imperial China was one of technological and intellectual sophistication in support of state power.