Sulechów (pronounced Sue-leh-hoof [suˈlɛxuf], German: Züllichau) is a town located within the Zielona Góra County, in Lubusz Voivodeship, western Poland.

The town centre is located about 22 km (14 mi) northeast of the regional capital Zielona Góra, where the national road 32 to Poznań crosses the expressway S3 to Gorzów Wielkopolski.

[3] The settlement itself was first mentioned in a 1319 deed, at the time when the warlike Ascanian margrave Waldemar of Brandenburg campaigned the area, occupying Sulechów and neighbouring Świebodzin.

[2] When the last Piast duke Henry XI of Głogów died without issue in 1476, inheritance claims were raised by his widow Barbara of Brandenburg and her father, the Hohenzollern elector Albrecht Achilles.

The Brandenburg influence met with fierce opposition by Henry's Piast cousin, Duke Jan II the Mad of Żagań, who nevertheless after several years of fighting had to sign an agreement, whereby the Silesian towns of Crossen (Krosno) and the town passed to the Margraviate of Brandenburg as a fief of the Bohemian (Czech) Kingdom,[4] an integral part of the Holy Roman Empire.

Along with Crossen, Sulechów, under the Germanized name Züllichau,[4] was incorporated into the Brandenburg Neumark district by 1535, ruled by Margrave John of Brandenburg-Küstrin who implemented the Protestant Reformation.

Two years later, the Piast duke Joachim of Münsterberg-Oels and his younger brothers officially waived any rights to the Crossen and Züllichau territories.