First found in Austria, where the name emerged in mediaeval times as one of the notable families of the region. From the 13th century the surname was identified with the great social and economic evolution which made this territory a landmark contributor to the development of the nation.

After the First World War, Austria became a republic. The Treaty of Versailles broke up the empire in 1919 and many of the Sudeten Germans were incorporated into the new nation of Czechoslovakia. In the 20th century, many Austrians migrated to other parts of Germany or Europe, as well as to North America. In the United States, the majority of settlers landed in Philadelphia, and moved on to Ohio, Texas, Illinois, California, New York, and Maryland. Many German settlers also migrated to Canada, particularly Ontario and the Prairies. Amongst the settlers in North America with this distinguished name Dahlen were Heinrich Dahlen, age 27; who arrived in America in 1776; Johann Dahler came to Canada in 1783; Sophie Dahlen settled in Texas in 1852; Martin Dahlem came to Philadelphia in 1856..

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