Geok Tepe, Gökdepe or Gokdepe, is a former fortress of the Turkmens, in Turkmenistan, in the oasis of Ahal, on the Transcaspian railway, 28 miles north-west of Ashgabat. Gökdepe is the Russian version of the Turkic name meaning "Blue Hill" from the Turkmen gök "blue" and depe "hill" or "summit".