The origin of Busko goes back to the 12th century, when a group of shepherds settled around St. Leonard's church. In 1185, Knight Dersław, the owner of Busko and its surroundings, brought Norbertine nuns, whom in his will he inscribed i.a. the village of Busko. Dersław was probably killed in the Battle of Chmielnik in 1241 (see: Mongol invasion of Poland). In 1251, it received a revenue privilege from King Bolesław V the Chaste "(Bolesław Wstydliwy)" allowing the convent to use the salt water. This is the first record of the use of Busko's mineral waters.