This house split into Swabian and Franconian branches, and its members came to prominence as Murgraves of Brandenburg.  
One member of this house gained hereditary lands in the Treaty of Krakow, which made him a vassal of the king of Poland.  A second member of this house replaced Alexander John Cuza and established this house's Sigmaringen branch, which ruled in Romania, and after the deposition of Isabella II, another member of this house was offered the throne of Spain but declined due to French opposition.  This house split into Swabian and Franconian branches, and its members came to prominence as Murgraves of Brandenburg.  For 10 points, name this family which included Frederick the Great and two Kaiser Wilhelms, and which ruled Prussia and the unified Germany.
One member of this house gained hereditary lands in the Treaty of Krakow, which made him a vassal of the king of Poland.  
House of Hohenzollern