The Northern Kingdoms or the Northern Realms, sometimes just referred to as the Four Kingdoms, are a group of human states north of the Amell mountains. Their inhabitants are called Nordlings by the Nilfgaardians (both the ones from the core of the Empire, and from the conquered provinces). Aside from humans, a number of dwarves, elves, gnomes, and halflings live in the Northern Kingdoms as second-class citizens.
The Northern Kingdoms were invaded and partially conquered by the Nilfgaardian Empire.
During the Third Northern War, only King Radovid V of Redania remained of all the crowned heads of the major kingdoms. For this reason, during this war the Northern Kingdoms were known as Radovid's Realms.
Upon the First Landing, and the arrival of humans on the Continent, the Northern Kingdoms were just large areas of uncolonised land inhabited by the Elder Races, and others races such as vrans and werebbubbs, before the eastward expansion of the people later known as Nordlings, around five hundred years ago.
First Northern War
Nilfgaard quickly took control of Marnadal, then slaughtered Cintra, causing the suicide of Calanthe. They then marched north into Sodden, taking control of Upper Sodden in a quick battle with a northern army. From there the Nilfgaardians crossed the Yaruga into Lower Sodden and were defeated in a massive battle, which resulted in more than 30,000 deaths and the defeat of the Nilfgaardian forces back past the mountains.