Tianxia (Chinese: 天下; literally "under heaven") is a phrase in the Chinese language and an ancient Chinese cultural concept that denoted either the entire geographical world or the metaphysical realm of mortals, and later became associated with political sovereignty.

In ancient China, tianxia denoted the lands, space, and area divinely appointed to the Emperor by universal and well-defined principles of order. The center of this land that was directly apportioned to the Imperial court was called Huaxia (Chinese: 華夏), Xia (Chinese: 夏), Hua (Chinese: 華), Zhongxia (Chinese: 中夏), Zhonghua (Chinese: 中華), or Zhongguo (Chinese: 中國), among other names, forming the center of a world view that centered on the Imperial court and went concentrically outward to major and minor officials and then the common citizens, and finally ending with the fringe "barbarians". The center of this world view was not exclusionary in nature, and outer groups, such as ethnic minorities, that accepted the mandate of the Chinese Emperor were themselves received and included into the Chinese tianxia.