Editing Theme (Byzantine district) (section)

=== Height of the theme system, 780s–950s ===
{{Expand section|date=May 2008}}[[File:Byzantine Empire Themata-950-en.svg|thumb|Byzantine ''themata'' in Anatolia, c. 950.]]
Despite the prominence of the themes, it was some time before they became the basic unit of the imperial administrative system. Although they had become associated with specific regions by the early 8th century, it took until the end of the 8th century for the civil fiscal administration to begin being organized around them, instead of following the old provincial system.<ref>{{Harvnb|Haldon|1999|pp=83–84}}</ref> This process, resulting in unified control over both military and civil affairs of each theme by its ''strategos'', was complete by the mid-9th century,<ref name="HaldonB84">{{Harvnb|Haldon|1999|p=84}}</ref> and is the "classical" thematic model mentioned in such works as the ''[[Kletorologion|Klētorologion]]'' and the ''[[De Administrando Imperio]]''.

At the same time, the need to protect the Anatolian heartland of Byzantium from the Arab raids led to the creation, in the later 8th and early 9th centuries, of a series of small frontier districts, the ''[[kleisoura (Byzantine district)|kleisourai]]'' or ''kleisourarchiai'' ("defiles, enclosures"). The term was previously used to signify strategically important, fortified mountain passages, and was now expanded to entire districts which formed separate commands under a ''kleisourarchēs'', tasked with guerrilla warfare and locally countering small to mid-scale incursions and raids. Gradually, most of these were elevated to full themes.<ref>{{Harvnb|Haldon|1999|pp=79, 84, 114}}</ref><ref>{{Harvnb|Kazhdan|1991|p=1132}}</ref>