Henryk IV Probus
Located within Poland since the establishment of the state in the 10th century, the settlement was first mentioned under the Old Polish name "Syczowe" in a document issued by Polish Duke Henryk IV Probus in February 1276. The name comes from the old Polish name Syc, who possibly was the owner of the settlement. According to another theory as well as folk traditions, the name comes from the Polish word "syty". Soon after it also appeared under the name "Wrathenberc", when a local castellan on the trade route to Kalisz in Greater Poland was documented. In the early 14th-century "Liber fundationis episcopatus Vratislaviensis" it appears under the names of "Syczow" and "Wartinbergk". After the fragmentation of Poland in 1138, Syców was part of the duchies of Silesia, Głogów (from 1291) and Oleśnica (from 1312). It was granted town rights before 1312. Duke Konrad I of Oleśnica, who inherited it in 1321, fell under Bohemian suzerainty as a vassal of King John of Bohemia in 1329, however the town remained under rule of local Polish dukes of the Piast dynasty until 1489.