Nordmark

History of Brandenburg and Prussia
Northern March pre–12th century		Old Prussians pre–13th century
Margraviate of Brandenburg 1157–1618 (1806)		Teutonic Order 1224–1525
		Duchy of Prussia 1525–1618	Royal (Polish) Prussia 1466–1772
Brandenburg-Prussia 1618–1701
Kingdom in Prussia 1701–1772
Kingdom of Prussia 1772–1918
Free State of Prussia 1918–1947			Klaipėda Region (Lithuania) 1920–1939 / 1945–present
Brandenburg (Germany) 1947–1952 / 1990–present	Recovered Territories (Poland) 1918/1945–present	Kaliningrad Oblast (Russia) 1945–present

The Northern March or North March (German: Nordmark) was created out of the division of the vast Marca Geronis in 965. It initially comprised the northern third of the Marca (roughly corresponding to the modern state of Brandenburg) and was part of the territorial organisation of areas conquered from the Wends. A Lutician rebellion in 983 reversed German control over the region until the establishment of the March of Brandenburg by Albert the Bear in the 12th century.

During the Migration Period, many Germanic peoples began migrating towards the Roman frontier. In the northeast they were replaced primarily by Slavic peoples (Veleti, later Lutici). The first Slavs were certainly in the Brandenburg area by 720, after the arrival of the Avars in Europe. These Slavs had come via Moravia, where they had arrived in the mid-seventh century. The remnants of the Germanic Semnoni were absorbed into these Slav groups.

The group of people who settled at the Spree river became known as Sprevani. They settled east of the line formed by the Havel and Nuthe rivers, in the current Barnim and Teltow regions. They built their main fortification at the confluence of the Spree and the Dahme rivers at Köpenick. The Hevelli lived west of that line, in the current Havelland and Zauche regions. They were named Habelli for the ancient Germanic name of the river "Habula" (Havel). The name for themselves was the Stodoranie. They built their main fortification at "Brenna" (modern Brandenburg). The Hevelli also built a large outpost at the current site of Spandau Citadel in Berlin. The Sprevani and Hevelli not only waged war against their German, but also their Slav, neighbours.

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Wikipedia