The earliest historically attested inhabitants were
Celts. In
Roman times, the area was part of the province of
Germania Superior, but after the rupture of the in 260, the area was settled by the
Alemanni. It remained a part of
Alemannia throughout the
Early Middle Ages and was a buffer zone between the central Alemannic lands and
Alsace, which was less strongly colonized by the Alemanni. The name of the region goes back to
Carolingian times, when most of modern Germany was divided into , territorial divisions similar to
shires or
counties. The Breisgau was then known as
Breisachgau, meaning the around the town of
Breisach on the east bank of the
Rhine. In the mid-9th century, it was a
march-like territory guarding the frontier with southern
Lotharingia and Alsace. In 859, it was bestowed on
Charles the Fat, the son of
King Louis I, a sign of its importance. In the 10th century, the Breisgau was within the
Duchy of Swabia and ruled by the
Zähringen family. In 1092 the Zähringer
Berthold II claimed the
Swabian ducal title but had to relinquish it to the
Staufer Frederick I in 1098; Berthold and his heirs would instead be known as the Dukes of Zähringen. In the Breisgau, the dukes of Zähringen founded
Freiburg, which became their chief city. In 1218 the ducal Zähringen line died out and the Breisgau passed to the
House of Baden, another Zähringer line (descended from Berthold II's brother
Herman) who had also detached themselves from Swabia in the 12th century as the
Margraviate of Baden. Within Baden Freiburg was ruled by the
Counts of Freiburg from the mid-13th century until 1368. () From the 13th/14th century, the area was part of
Further Austria (the ), the area in southwest Germany ruled by the Austrian
Habsburgs. In 1797 the Breisgau, along with the rest of the , was ceded to
Ercole III d'Este,
Duke of Modena and Reggio, as compensation for
his losses to the French
Cispadane Republic (
Cisalpine Republic from 1797); it passed to his heir
Ferdinand Karl of Austria-Este following his death in 1803. In 1805, by the
Treaty of Pressburg, the area was ceded to the
Electorate of Baden (the
Grand Duchy of Baden from 1806). == Borders and area ==