Kuyavia (Polish: Kujawy; Latin: Cuiavia), also referred to as Cuyavia, is a historical region in north-central Poland, situated on the left bank of Vistula, as well as east from Noteć River and Lake Gopło.

The name Kuyavia first appeared in written sources in the 1136 Bull of Gniezno (Polish: Bulla Gnieźnieńska, Latin: Ex commisso nobis) issued by Pope Innocent II, and was then mentioned in many documents from medieval times.

The capital of this Duchy, and - from the late 14th century - the residences of the Voivode governors were Inowrocław, Brześć Kujawski, and Radziejów as the seat of the shared regional Sejmik council of the two voivodeships.

[6] Some ethnographers and historians, for example Oskar Kolberg and Zygmunt Gloger, count the lands of Dobrzyń and Chełmno north-east of the Vistula as parts of the Kuyavia region.

The Goplans, which some researchers identify with the Mazowszanie-Kłobianie or simply with the Kuyavians, had created a country with the main centers in Kruszwica on the northern shore of Lake Gopło.

According to Andrzej Bańkowski, the Polans had moved into the region of Greater Poland after they had to leave together with the Morawianie, their former Pannonian territories, conquered by the Avars.

As a result of occupation of the Goplans' territory, the lands of Kuyavia were under the strong influence of the Pannonian culture and they lost their primary Masovian spirit.

When the name Cuiavia arose for the first time in the 1136 Bull of Gniezno, it referred to the lands east of Greater Poland around Kruszwica and Włocławek, bordering with the Vistula river.

[10] In 1306 Ziemomysł's son Casimir II swore allegiance to his uncle Władysław I, who began to re-unite the Lands of the Polish Crown under his rule.

The duchy was devastated during the Polish–Teutonic War of 1326–32, culminating in the 1331 Battle of Płowce, but was finally restored to Poland by the Teutonic Knights in the 1343 Treaty of Kalisz.

While the Brześć Kujawski province (counties: Aleksandrów, Radziejów and Włocławek) remained with the Masovia Governorate of Congress Poland in Russian Empire, Inowrocław (Hohensalza) and Bydgoszcz (Bromberg) was incorporated into the Prussian Grand Duchy of Posen.

The Polish population was subjected to various crimes, such as mass arrests, imprisonment, slave labor, expulsions, kidnapping of children, deportations to Nazi concentration camps and extermination, incl.

Major sites of massacres of Poles in the region included Gniewkowo, Fordon, Otorowo, Buszkowo, Tryszczyn, Odolion and Borówno.