Zähringen is an old German noble family from Swabia, which founded a large number of cities in the area that is today Switzerland and the German state of Baden-Württemberg. The name is derived from Zähringen castle near Freiburg im Breisgau, now in ruins, which the family founded in 1120.
While the junior line which first assumed the title of Duke of Zähringen became extinct in 1218, the senior line (known as the House of Baden) persists and currently uses the title of “Margrave of Baden, Duke of Zähringen”. In the German language, the word Zähringer is used for “House of Zähringen”.
Refer Chapter 10.9 of The King’s Son (The Evidence) for details on my analysis relating to the BADEN House YDNA Haplogroup.