The deity Chi You was the leader of the Jiu Li Tribe (九黎部落 jiǔ lí bù luò) in ancient times, he was a skilled weapon smith and master of war.
There are many different accounts of what Chi You actually looked like. In some versions he has eight bull-like legs, three heads and six arms, a copper head and an iron forehead. In other versions he only has two legs, one head, four eyes, and four arms. Some also describe him as having the head of a bull and a pair of wings. All accounts, however, agree that he had horns on his head and that he was virtually invulnerable (刀枪不入 dāo qiāng bù rù – neither sword or spear could penetrate him).
As a master weapon smith, Chi You was an expert with the sword, axe, and Ge (戈 gē) – an ancient Chinese weapon, similar to a halberd, but better described as a dagger-axe. He was renowned for his bravery and unwillingness to give up without a fight.
Chi You, Yan Di and the Yellow Emperor
According to legend, after Chi You defeated Yan Di (炎帝 yán dì) in the battle of Ban Quan (阪泉之战 bǎn quán zhī zhàn), Yan Di formed an alliance with the Yellow Emperor (黄帝 huáng dì) to take Chi You down together. After an epic battle in Zhou Lu (涿鹿 zhuō lù) where Chi You lead 81 of his brethren to fight, Chi You was finally defeated.
“81 brethren” is said to represent 81 different factions or tribes, or, 81 brethren that were all extraordinary, brave and powerful fighters - each with a copper head and iron forehead.