Regions of Turkey

The 1st Geography Congress, held in Ankara between 6-21 June 1941, divided Turkey into seven regions after long discussions and work. These geographical regions were separated according to their climate, location, flora and fauna, human habitat, agricultural diversities, transportation, topography and so on. At the end, 4 side regions and 3 inner regions were named according to their neighborhood to the four seas surrounding Turkey and positions in Anatolia.

Distinct contrasts between the interior and periphery of Turkey are manifested in its landform regions, climate, soils, and vegetation. The periphery is divided into the Black Sea region, the Marmara region, the Aegean region, and the Mediterranean region. The interior is also divided into three regions: the Pontus and Taurus mountain ranges, the Anatolian Plateau, and the eastern highlands. The seventh region of the country is the Arabian Platform in the southeast, adjacent to the Syrian border
Black Sea
Marmara
Aegean
Mediterranean Sea
Central Anatolia
East and Southeast Anatolia

Further more readings

http://www.worldturkey.com/lang/eng/regions.php

http://en.wikipedia.org/wiki/Geography_of_Turkey