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 of Poland been between 922–945; the activity of the Duke in his final years of life puts the date of his birth closer to the latter year. There are three major theories concerning the origin and meaning of Mieszko I's name. The most popular theory, proposed by Jan Długosz, explains that Mieszko is a diminutive of "Mieczysław", a combination of two elements or lexemes: "Miecz" meaning sword and "Sław" meaning famous. Today, this theory is rejected by the majority of Polish historians, who consider the name Mieczysław to have been invented by Długosz to explain the origin of the name Mieszko. Today,