Mieszko I of Poland Abraham ben Jacob. According to him, Mieszko I had fought against the Weltaba tribe, commonly identified with the Veleti. Wichmann the Younger, a Saxon nobleman who was then a leader of a band of Polabian Slavs, defeated Mieszko twice, and around 963 a brother of Mieszko, whose name is unknown, was killed in the fighting. The frontiers at the mouth of the Oder River were also desired by the German margraves. In addition, the Veleti Bohemia, which at that time possessed Silesia and Lesser Poland regions, constituted a danger for the young state of the Polans. The chronicle of Thietmar
Mieszko I, Duke of Cieszyn was on 1 January 1290. In internal politics he pursued vigorous policies. Mieszko carried out intensive colonizing policies and founded many settlements. He also gave city rights to several towns: Cieszyn, Oświęcim (in 1291), Bielsko, Skoczów and Fryštát. On 10 November 1292 he granted the city rights to Zator. Mieszko refused to support any of the Piast pretenders to the Polish throne (Henry IV Probus, Przemysł II and Władysław I the Elbow-high). Instead he stood alongside King Wenceslaus II of Bohemia. On 17 January 1291 the formal agreement was signed in Olomouc which formed the alliance between the Bohemian Kingdom,