Ciechanów Land

The history of Ciechanów Land dates back to the late 13th century, when a system of castellanies was established in the province of Mazovia.

In the late 14th century, following the example of the Kingdom of Poland, Mazovian dukes decided to introduce a new system of lands, divided into counties.

Furthermore, in 1471–1495, the Duchy of Ciechanów existed, with a size of 8200 km2, and such towns as Łomża, Zakroczym and Różan.

In 1526, following the death of Duke Janusz III of Masovia, all of Mazovia was annexed by Poland, and the Masovian Voivodeship was established.

Local residents colonized the neighboring lands of Podlasie, Lithuania, Prussia (see Masurians), Volhynia and Pomerelia.