The Neumark ( listen (help·info)), also known as the New March (Polish: Nowa Marchia) or as East Brandenburg (German:  Ostbrandenburg (help·info)), comprised a region of the Prussian province of Brandenburg, Germany, located east of the Oder River in territory which became part of Poland in 1945.

Called the Lubusz Land while part of medieval Poland, the territory later known as the Neumark gradually became part of the German Margraviate of Brandenburg from the mid-13th century. As Brandenburg-Küstrin the Neumark formed an independent state of the Holy Roman Empire from 1535 to 1571; after the death of the margrave John, a younger son of Joachim I Nestor, Elector of Brandenburg, it returned to Elector John George, the margrave's nephew and Joachim I Nestor's grandson. With the rest of the Electorate of Brandenburg, it became part of the Kingdom of Prussia in 1701 and part of the German Empire in 1871 when each of those states first formed. After World War I the entirely ethnic German Neumark remained inside the new Weimar Republic of Germany.

Brandenburg ( listen (help·info); Low German: Brannenborg, Lower Sorbian: Bramborska; Upper Sorbian: Braniborska) is one of the sixteen federal-states of Germany. It lies in the east of the country and is one of the new federal states that were re-created in 1990 upon the reunification of the former West Germany and East Germany. The capital is Potsdam. Brandenburg surrounds but does not include the national capital and city-state of Berlin.

Originating in the medieval Northern March, the Margraviate of Brandenburg grew to become the core of the Kingdom of Prussia, which would later become the Free State of Prussia. The eastern third of historic Brandenburg (Ostbrandenburg/Neumark) was ceded to Poland in 1945.

In late medieval and early modern times, Brandenburg was one of seven electoral states of the Holy Roman Empire, and, along with Prussia, formed the original core of the German Empire, the first unified German state. Governed by the Hohenzollern dynasty from 1415, it contained the future German capital Berlin. After 1618 the Margraviate of Brandenburg and the Duchy of Prussia were combined to form Brandenburg-Prussia, which was ruled by the same branch of the House of Hohenzollern. In 1701 the state was elevated as the Kingdom of Prussia. Franconian Nuremberg and Ansbach, Swabian Hohenzollern, the eastern European connections of Berlin, and the status of Brandenburg's ruler as prince-elector together were instrumental in the rise of that state.