During the beginning of the 17th Century, Ukrainian Cossacks were first based in that area. The settlement was first mentioned in 1635 in various documents as Novoselitsa. In 1642 a Polish fortress was built in that place named after the river Konotopka. Probably the river disappeared, and another one was created, Yezuch. The fortification became a key point in the struggle against the Moscow state. Some historians suppose that Konotop was inhabited even before the Tatar-Mongolian invasion.