in 1388, the hongwu emperor established contact with three tribes of the jianzhou jurchens, the odoli, huligai and tuowen and attempted to enlist them as allies against the mongols. there was a general migration south of the various jurchen groups around the start of the 15th century and the three tribes established themselves around the tumen river (near the modern border of china, russia and north korea). not long afterwards, the various jurchens began accepting ming titles from the yongle emperor as the military commanders of the three wei, namely jianzhou wei (), jianzhou left wei () and jianzhou right wei (). the wei () was military unit composed of 5 suo (), and each suo was staffed with 1100 soldiers. as military commanders of wei, they were required to go to beijing every year to pay tribute to the emperor.