燕简公 / Duke Jian of Yan
燕简公 / Duke Jian of Yan appears in Zhouji 09 as the elderly ruler of 燕国 during the early Warring States melee. The source names Yan as the state attacked by 齐国 when Qi occupies Sangqiu.
His source role is contextual rather than biographical. Yan’s vulnerability draws in 韩国, 赵国, and 魏国, whose rescue attack on Qi becomes one starting point for the episode’s interstate-war frame.