[1] The state was formed on 17 November 1370, when King of Poland, Louis I of Hungary, had given Vladislaus II of Opole territory of Wieluń Land as his own duchy.

Vladislaus II was given those lands due to his help to the king in the process of legal succession of the throne of Poland.

[4][3] In the spring of 1376, Vladislaus II had sent his knights to join forces led by Sędziwój Pałuka against Władysław the White in his rebellion against the Polish king.

Around that time, the state was subdivided into districts of Wieluń, Ostrzeszów, Olsztyn, Krzepice, Brzeźnica and Bolesławiec.

On 15 September 1391, Jagiełło's forces had entered Wieluń, beginning the war theatre on the territories of the duchy.