The County of Brunswick was a county in the medieval Duchy of Saxony. It existed from about the 9th century until 1235, when it was raised to a duchy, the Duchy of Brunswick-Lüneburg.
The county developed out of the possessions of the Brunonen dynasty centered on the town of Brunswick and was enlarged by the inheritances of Henry the Fat of Northeim around Northeim and Göttingen and a part of the Billung inheritance around Lüneburg, which fell to the House of Welf in 1106. When the Duchy of Saxony was reorganized in 1180, the county became de facto independent from the Duchy, since the new Ascanian dukes could not establish control over it. In 1203, the three sons of Duke Henry the Lion divided the county among themselves; Henry received the western part including Hannover and Göttingen, William received the area around Lüneburg, and King Otto IV the area around Braunschweig. The independence of Brunswick was recognized when it was raised to the Duchy of Brunswick-Lüneburg in 1235, which would exist until 1918.
