The origins of a future dynasty are first recorded. The Counts of Zollern are first mentioned in 1061. The counts of Zollern are located between the Neckar and Danube Rivers in the Black Forest region southern Wüettemburg. Their name was changed to Hohenzollern in 1200s when the first castle was built on a mountain top (Hohe =Height) Their family eventually became the rulers of Brandenburg and Prussia. Kaiser Willhelm II was the ninth and last Hohenzollern to rule over Prussia. A researcher of this principality should realize that Hohenzollern was combined with Baden and Wuerttemberg in 1952 to form the state of Baden-Wuerttemberg. Many records will be listed under Baden-Wuerttemberg rather than under Hollenzollern. Hohenzollern-Sigmaringer and Hohenzollern-Hechingen was a Roman Catholic State.
http://history-world.org/House Of Hohenzollern.htm
http://www.preussen.de/de/heute.html (House of Hohenzollern)
http://www.preussen.de/de/heute/burg_hohenzollern.html (Castle of Hohenzollern)
http://www.hohenzollern.com/ (Castle Sigmaringen)