The war was fought likely for the purposes of territorial expansion, with Polish ruler duke
Mieszko I taking over the lands of the
Vistulan tribe (
Lesser Poland area, with the major settlements of
Sandomierz and
Kraków) in the years 998–999. The Bohemian duke
Boleslaus II contested Mieszko's actions, and their armies clashed in Silesia. The Bohemians received aid from the
Veleti, while the
Holy Roman Empire helped the Poles and after a short conflict the Bohemians were defeated, with Mieszko also acquiring Silesia for Poland (with territories around
Krosno and
Niemcza). Thietmar, however, while devoting some space to the conflict itself, did not discuss the reasons for it, which modern historians can only speculate about. There is also evidence that Mieszko might have controlled parts of Silesia as early as mid-980s, and it has been speculated that the reason for the war might have not been over Lesser Poland, but about the territorial disputes in Silesia itself. == Aftermath ==