The greater part of the (Romanian) German population lived in massive, coherent enclaves such as those in the erstwhile Hungarian territories of Transylvania, Banat and Sathmar; in Bessarabia, Bukovina and the Dobregea; and in smaller settlements in the so-called Regat (pre-World War I Rumania). The Danube Swabians lived in the western border lands in Banat (281,067) and Sathmar region (21,845), adjacent to Hungary. There existed also a smaller group of them (12,439) in the Dobregea in the eastern-most end of the Danube valley. [excerpted from The Danube Swabians: German Populations in Hungary, Rumania and Yugoslavia and Hitler's Impact on their Patterns, by Geza C. Paikert]
Nevertheless, as a result of a number of WWII era developments, the present size of Romania's German-speaking minority is less than half of what it was in 1939. The main causes of the massive reduction can be summarized thusly: (a) Upon transferring certain territories near the Black Sea from Romanian to Russian jurisdiction in 1940, Hitler had 68,000 ethnic Germans from the Bukovina, about 80,000 from Bessarabia, and approximately 15,000 from the Dobruja resettled in Germany along the Warthe, a tributary of the Oder River, and in other areas. [excerpted from Tracing Romania's Heterogeneous German Minority from its Origins to the Diaspora, by Jacob Steigerwald listed below]