An Chonghui became Li Siyuan's chief of staff shortly after Li Siyuan became emperor in 926, and fell from grace in 931, so Feng Meng's commission must have occurred during that period, and Shi Jingtang's commission limited that period further to 926 to 928. See Zizhi Tongjian, vols. 275, 277.
Feng Yun apparently became Hedong's military governor in 930 and was shortly after moved to Zhongwu Circuit (忠武, headquartered in modern Xuchang, Henan) instead, so Feng Yu's service under him must be in that short duration. See New History of the Five Dynasties, vol. 27.
