In antiquity, the earliest foot supports consisted of riders placing their feet under a girth or using a simple toe loop. Later, a single stirrup was used as a mounting aid, and paired stirrups appeared after the invention of the treed saddle. The stirrup was apparently invented in China in the first few centuries A.D. and spread westward through the nomadic peoples of Central Eurasia. The use of paired stirrups is credited to the Chinese Jin Dynasty and came to Europe during the Middle Ages. Some argue that the stirrup was one of the basic tools used to create and spread modern civilization, possibly as important as the wheel or printing press.