The Battle of Chengpu took place in 632 BC between the State of Jin and the State of Chu and its allies during the Spring and Autumn period of Chinese history. It was the first major battle in the protracted conflict between the states of the Yellow River valley, and the states of the Yangtze River valley. The Jin victory confirmed the hegemony of Duke Wen and checked Chu ambitions in the north for a period.
Background
Following the death of Duke Huan of Qi in 643 BC, the state of Chu steadily extended its influence northward, absorbing half a dozen smaller states as its satellites. In 636 BC, Chong'er, a ducal prince of Jin, after nineteen years in exile traveling throughout numerous states, came to power as Duke Wen of Jin with the help of Duke Mu of Qin. Duke Wen assumed a position of leadership among the states and instituted numerous domestic reforms.
In the years leading up to 632 BC, conflict between Jin and Chu became increasingly public and was characterized by frequent shifts in alliances between the various small states that lay in a narrow band of land between the two larger states.