Hohenzollern-Sigmaringen – Flag in Lexicon and Shop https://www.flaggenlexikon.de/fdthohes_me.htm
The Principality of Hohenzollern-Sigmaringen existed between 1623 and 1848. It became part of the Prussian administrative district of Hohenzollernsche Lande in 1850. The flag showed the colors black and white.
Wuerttemberg-Hohenzollern fused with Wuerttemberg-Baden