First found in Hessen, where the name was closely identified in early mediaeval times with the feudal society which would become prominent throughout European history. Diez, the geographical origin of the name, is a town with a castle (later a prison) that belonged to the counts of Nassau-Dillenburg, in what was Hesse-Nassau. The name would later emerge as a noble family with great influence, having many distinguished branches, and become noted for its involvement in social, economic and political affairs.

Some of the first settlers of this family name or some of its variants were: Anna Dietz, age 40; who settled in New York state in 1876; Conrad Dietz who arrived with his wife and children in America in 1738; and Jacob Dietz, age 20.

For more information on the last name Diez, the PDF Surname History is available for purchase as well as other products.