Northern Masovia is the geographic term for the historical region bordered by major rivers to the south (Bug and Vistula) and to the east (Narwa and Biebrza) while its northern and western boundaries were delimited by early medieval ethno-geographic entitites such as the Dobrzynska Land and the Old Prussian & Yatvingians Territories. In this region, the early medieval strongholds were erected in quite distinct surroundings, difficult to access and easy defendable on hilltops with abrupt gradients, on isles or peninsulas, or in the midst of swampy areas.  As such these man-made objects were networked accordingly to the natural terrain conditions, being located on arable soils. Their geographic classification distinguishes two groups: the first comprised of strongholds situated at the riverfront and the second group made of those strongholds whose location is dependent on the location of the first class of strongholds.