Complex sentence: Donaueschingen lies on the Baar plateau in the southern Black Forest at the confluence of the Brigach and Breg rivers--the two source tributaries of the Danube River--from which the town gets its name.
Split into simpler sentences: Donaueschingen lies on the Baar plateau in the southern Black Forest. The confluence of the Brigach and Breg form the source of the Danube river from which the town gets its name.