The Taiping Heavenly Kingdom developed a complicated peerage system for noble ranks.
There were five ranks of wang: Below the king or prince, there were six ranks of nobility (Chinese: 六等爵) in Taiping Heavenly Kingdom: E (義 Yì), An (安 Ān), Fu (福 Fú), Yen (燕 Yān), Yü (豫 Yù) and Hou (侯 Hóu).
E and An were most highest ranks of the nobility, once they were very noble titles of the Taiping Heavenly Kingdom.
If the Heavenly King wanted to promote someone, he gave the person either E or An.
However, this rule was challenged after 1860 because the nobility titles had been given too freely.