Treia is a municipality located in the district of Schleswig-Flensburg in the northern German state of Schleswig-Holstein. It is situated in the Schleswig region of this historically significant state.
As a municipality in rural Schleswig-Holstein, Treia is part of the wider administrative framework of the Schleswig-Flensburg district. The area is characterized by the northern German landscape typical of Schleswig-Holstein, which borders Denmark and has a history shaped by Scandinavian and German cultural influences.