'North'), is a geographical term that refers to a relatively large and fertile area, consisting of the southern border of the Caspian Sea and the Alborz mountains.
It includes the provinces of Gilan, Mazandaran, and Golestan (ancient kingdom of Hyrcania, medieval region of Tabaristan).
[1] The major provinces, Gilan and Mazandaran, are covered with dense forests, snow-covered mountains and impressive sea shores.
The major cities are Rasht, Gorgan, Sâri, Bâbol, Babolsar Amol, Qaem Shahr, Gonbad-e Kavus, Anzali, Lahijan and Behshahr.
From the northeast, Khorasan which is a large province laid out from the north to the middle south of Iran and is a neighbor to the Afghanistan border.
The earliest references to the language of Mazandaran, called Tabari, are to be found in the works of the early Muslim geographers.
In the western side of Gilān people speak some sort of Gilaki which is heavily mixed with Āzari Turkish, the language of the neighboring province.