theme
A Byzantine term that signifies wide military and administrative units under the administration of a strategos (general). The institution was consolidated in the 7th century and was characteristic for the organization and the division of Byzantine Empire at the Middle Byzantine period. The term applies also to the army unit that resided in each administrative unit and was staffed by farmer-soldiers. The thematic system was maintained until the end of Byzantine period. However, in the Later Byzantine period it was used in order to declare mostly tax units.