Golestan derives its name from a wider region known historically as Gorgân (گرگان), Middle Persian Gurgān, and Old Persian Varkāna (in the Behistun Inscription) meaning "land of wolves".[8] This is also the root of the Ancient Greek Υρκανία (Yrkania) and Latin Hyrcania.
Wild wolves are still found in Golestan. Human settlements in this area date back to 10 000 BC. Evidence of the ancient city of Jorjan can still be seen near the current city of Gonbad-e Kavus. It was an important city of Persia located on the Silk Road.
Under the Achaemenid Iran, it seems to have been administered as a sub-province of Parthia and is not named separately in the provincial lists of Darius and Xerxes. The Hyrcanians, however, under the leadership of Megapanus, are mentioned by Herodotus[9] in his list of Xerxes’ army during the invasion of Greece Apparently, the Mazandaranis who inhabit the foothills all the way to Shah Pasand were subsumed under the rubric "Persian" by this official statistics.
The Persians and Mazandaranis are considered by nearly all inhabitants of the province to be "the old natives" while all others are considered ethnic immigrants in the past.
Most Mazandaranis live in Gorgan, Ali Abad, Kordkuy, Bandar-e Gaz and Gonbad-e Kavus. They speak Mazanderani language.The Turkmens reside in the north of the province, a plain called Turkmen Sahra. From the 15th century, these formerly nomadic people have lived in this area, the main cities of which are Gonbad-e Kavus and Bandar Torkaman. Turkmens are Muslim and follow the Hanafi school of Sunni interpretation. They are a sizable minority at cities such as Gorgan, Ali Abad, Kalaleh and many of eastern townships.
Azeris and the Qizilbash predate the Turkmen by centuries and have in time become completely Shia, and therefore, culturally associate with the Persians and other Shias.
The Sistani Persians and the Baluch are relatively of recent arrival and date back to the early 20th century. They are still arriving into the area in some numbers due to the lasting drought in their home areas of Sistan.
Other ethnic groups such as Kazakhs, Georgians, and Armenians also reside in this area, and have preserved their traditions and rituals.
A small minority of Bahá'í Faith also live in Golestan (in Shahpassand).source:wikipedia