Dilek Peninsula-Büyük Menderes Delta National Park Aegean Region in general. The peninsula was shaped into its current form over several geological eras with the tectonic merging of Paleozoic schist formations, Mesozoic limestone and marble deposits, and finally the accretion of large clays and other sediments during the Neogene period. This is partly because of Turkey's unstable fault block terrain, and because of the close proximity of the Anatolian-Aegean plate boundary, which generates massifs of mountains all across western Turkey. This includes the peninsula and the mountains surrounding the Büyük Menderes River, known collectively as the Menderes Massif. The peninsula is highly mountainous, with most of its
Anatolian beyliks with the Battle of Köse Dağ in 1243 which had the indirect consequence of extending the Turkic territory in Western Anatolia toward the end of the 13th century. Three Anatolian regions remained Christian until their defeat and Ottoman conquest: Combined with the Seljuqs and the immigration of Turkic tribes into the Anatolian mainland the Anatolian Beyliks spread Turkish and Islamic influence in Anatolia. Unlike the Seljuqs, whose language of administration was Persian, the Anatolian emirates adopted spoken Turkish as their formal literary language. The Turkish language achieved widespread use in these principalities and reached its highest sophistication during the Ottoman