Tian Wang (天王), translatable as either "heavenly prince," "heavenly king" or "wearer of the blue apron" was a
Chinese regal title that was most frequently used during the
Sixteen Kingdoms era, among the kingdoms founded by members of the
Wu Hu tribes, often used as an intermediate stage from claiming a prince/king (王,
wang) title to an
emperor (皇帝,
huangdi) title. However, for most intents and purposes, a
tian wang was treated as an emperor—their spouses carried empress titles, their styles were the same as emperors, and their
posthumous names and
temple names reflected imperial status. The only difference appeared that when the head of the state carried the
tian wang title, the highest rank among nobility usually became duke (公,
gong) rather than prince.