Wang Meng (王猛, pinyin Wáng Měng) (325–375), courtesy name Jinglüe (景略), formally Marquess Wu of Qinghe (清河武侯), served as prime minister to the Former Qin emperor Fu Jiān in the fourth century. Under his governance, Fu Jiān's empire expanded from encompassing only most of Shaanxi, eastern Gansu, and extreme western Shanxi and Henan, to covering nearly all of then-Chinese territory north of the Huai River and the southwest. He is commonly regarded as one of the greatest statesmen in Chinese history.
Wang Meng, ethnically Han, was poor in his youth, when he lived in the Later Zhao capital Yecheng, and he made a living by making bamboo grain containers for shreshing. Despite his intelligence, his talents were not discovered by Later Zhao officials. The intelligentsia also largely refused to associate with him, since he was unkempt in his appearance. He later became a hermit at Huayin Mountain, in the territory of Former Qin, ruled by the Di Fu clan, after Later Zhao's collapse.
When the Jin general Huan Wen made a major attack on Former Qin in 354 and reached all the way to Ba River (灞水), in the vicinity of Former Qin's capital Chang'an, Wang went to meet Huan. Wang, as unkempt as he was, was using his hand to slap at fleas and ticks during the conversation, but impressed Huan with his knowledge and tactics. Huan then asked him why the people of the Qin lands were not shifting their allegiance to Jin, and Wang pointed out that the people were not sure what Huan's intentions were, given that he hesitated at crossing the Ba River. As the situation stalemated, Huan began to run out of food supplies and was forced to withdraw. He invited Wang to withdraw with him, but Wang declined, apparently believing that Huan was not the right person to follow.