Thesion (IPA: /ˈθɛsiən/; also /ˈθɛsjən/, Thesionite Lokrenian /ˈθiːʒən/) is a duchy of Lokren, located east of the Forest of Piges, between the frontier territories (i.e., Ormetland and Chasadon) and the Old Kingdom.

Thesion is situated almost entirely on a high plateau of rolling hills and good farmland. Most of the province is given over to agriculture.