Over the next century, a four-way balance of power developed between Qin (west), Jin (west-center), Chu (south) and Qi (east), with a number of smaller states between Jin and Qi. In 627BC, Jin defeated Qin while it was attacking Zheng. Jin invaded Qin in 625BC and was driven back the following year. In 598BC, Chu defeated Jin at the Battle of Mi. In 589BC, Jin defeated Qi, which had invaded Lu and Wei. About this time Jin began to support the southeastern state of Wu as a means of weakening Chu. Duke Li of Jin (580-573) allied with Qin and Qi to make an east-west front against the threat of Chu from the south. In 579BC, a minister of the state of Song arranged a four-power conference in which the states agreed to limit their military strength. Four years later, fighting broke out again; Jin and its allies defeated Chu at the battle of Yingling. Duke Dao of Jin (572-558) strengthened the state by internal improvements rather than external wars. He absorbed a number of Rong tribes and was recognized as Hegemon.