Mengjin began its life as an ancient ferry crossing for the Yellow River. According to legend, King Wu of Zhou crossed the Yellow River at this location, after forming an alliance (盟/méng/alliance + 津/jīn/ferry crossing) with the other nobles. One theory goes that the original name was actually 盟津 (literally: the ferry crossing of the alliance) rather than 孟津 (盟 and 孟 are both rendered as Meng). According to this theory, it was only in later times that the character 盟 was mistakenly replaced by 孟. The ferry crossing was an important strategic location during times of war.