Zanjan Province

Zanjan (Azerbaijani: زنجان; Persian: زنجان) is a province located in the North-West Iran with the Zanjan city being its center. Zanjan province with an area of 36,400 km² has a mostly rural, population of 1.7 million. The province lies 330 km northwest of Tehran, connected to it via a freeway.
Zanjan also has an incredible cave called katale khor. It is near the Sultaniyeh.

History
The history of Zanjan has close connections to that of Azarbaijan. Zanjan was always one of the important city in Azarbaijan. The name of Azerbaijan derives from Atropatesو a Iranian satrap of Media under the Achaemenid empire, who later was reinstated as the satrap of Media under Alexander of Macedonia.The original etymology of this name is thought to have its roots in the ancient Zoroastrianism, namely, in Avestan Frawardin Yasht ("Hymn to the Guardian Angels"), there is a mentioning of: âterepâtahe ashaonô fravashîm ýazamaide, which literally translates from Old Persian as "we worship the Fravashi of the holy Atare-pata" . Atropates ruled over the region of present-day Iranian Azerbaijan.
In Ptolemy's Geography, the city is referred to as Aganzana. It is said that the Sassanid king Ardashir I of Persia, reconstructed the city and called it Shahin but later it was renamed to Zangan, of which the present name is the arabicized form of.
In past times Zanjan's name was Khamseh, which means "province with five tribes".