Johann Christoph Rau, a physician (Arzt), and his family (2 unnamed sons; 1 unnamed daughter) immigrated to Denmark (Schleswig-Holstein), arriving in Fridericia on 22 October 1759. Records there indicate that he also served as a sergon (Chirurg) with a Danish regiment. They are last recorded among the Danish colonies on 26 April 1763.
Johann Christoph Rau, a physician (Arzt), his wife Susanna, and sons (Jeremias, age 11; Johann Peter, age 8) are recorded on the 1767 census of Dobrinka in Household No. 7. They settled had settled there on 29 June 1764.
The 1767 census records that Johann Christoph Rau came from the German village of Freiwalde in Brandenburg. The Eichhorn book records that he came from the German village of Leutershausen near Heidelberg in the Kurpfalz region - which is more probable.
- Eichhorn, Alexander, Jacob & Mary Eichhorn. The Immigration of German Colonists to Denmark and Their Subsequent Emigration to Russia in the Years 1759-1766 (Deiningen, Germany: Drukerei und Verlag Steinmeier GmbH & Co. Kg, 2012): B-1303.
- Mai, Brent Alan. 1798 Census of the German Colonies along the Volga: Economy, Population, and Agriculture (Lincoln, NE: American Historical Society of Germans from Russia, 1999): Db63, Db77.
- Pleve, Igor. Einwanderung in das Wolgagebiet, 1764-1767 Band 1 (Göttingen: Der Göttinger Arbeitskreis, 1999): 315.