Kingdom of Polandball was an historical countryball. Despite his flag not being rectangular shaped, this country is named -ball. The non-ball version is more like an Anschluss form.
From the 12 century to the 14th century Poland was in a long period of fragmentation (1138–ca. 1314). During the fragmentation Poland lost Silesia and Pomerania. After the re-unitary Poland started to conquer the east territory. Poland gained a part of Ukraine clay, including Lwów.
In mid-1320s an agreement between king of Poland, Władysław Łokietek, and Grand Duke of Lithuania, Gediminas, was made. Gediminas daughter Aldona married Władysław Łokietek's son and future successor, Casimir III of Poland, in 1325, which led to improved relations.
In 1385 the growing threat of the Teutonic Order to both countries led to a firmer alliance - the Polish-Lithuanian union, which is the end of the Piast dynasty and the beginning of the Jagiellonian dynasty.
On 10 November 1444 Poland lost king fighting Kebab in Varna, did not into king for many days before becoming Elective Monarchy
In 1569, Poland and Lithuania merged into a single nation - Poland-Lithuaniaball, ending the Jagiellonian dynasty.