Middle Turkic refers to a phase in the development of the Turkic language family, covering much of the Middle Ages (c. 900–1500 CE). In particular the term is used by linguists to refer to a group of Karluk and Oghuz and related languages spoken during this period in Central Asia, Iran, and other parts of the Middle East occupied by the Seljuk Turks. Its best known literary form is the Karakhanid dialects spoken in Kashgar, Balasaghun and other cities along the Silk Road. The literary language of the Chagatai Khanate is considered a later form of Middle Turkic. Confusingly, the Karluk and Oghuz "Middle Turkic" period overlaps with the East Turkic Old Turkic period, which covers the 8th to 13th centuries.