First found in Brandenburg, where the name could be considered to have made a great early contribution to the feudal society which became the backbone of modern Europe. The name became prominent in local affairs and branched into many houses which played important roles in the tribal and national conflicts, with each group seeking power and status in an ever changing territorial profile. Chronicles first mention Albrecht Rorer, or Albrecht "from the Ror," who was born in Eger in Bohemia around 1330.

Much of German history has been shaped by the state of Prussia. It was an enduring military power until after the Second World War. At that time, the state was abolished altogether and its land divided between the Soviet Union, Poland, East Germany and West Germany. While some Prussians were content to remain in those countries, others moved away, many of them migrating to North America. They entered the United States mostly through Philadelphia, moving on to Ohio, Texas, Illinois, California, New York, and Maryland. Others went to Canada, settling on the prairies and in the province of Ontario. Among those of this surname listed in various historical records were: Johannes Roar, who sailed to Philadelphia in 1728. Among the many others to follow this first settler were: Baltzar Roer, who sailed to Philadelphia in 1729.

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