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.

The state of Prussia was a great influence on the shape of modern Germany. After the Second World War, Prussia's land was divided among the Soviet Union, Poland, East Germany and West Germany and the state was abolished. Some Prussians remained in those countries after the war, while many others migrated to North America in search of a new start. Philadelphia was their primary point of entry to the United States, after which many of them moved on to Ohio, Texas, Illinois, California, New York, and Maryland. A large number of Prussians also migrated to Ontario and the prairie provinces as United Empire Loyalists. Analysis of immigration records has shown some of the first Rors to arrive in North America, and among them 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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