The township of Zanjan is composed of two large valleys known as 'Zanjan Rood' and 'Sefid Rood'. In between which the Qanavol and Angooran Mountains lie. Zanjan has moderate summers and cold winters. The distance between Zanjan and Tehran is 328 km. Zanjan was founded during the reign of Ardeshir Babakan and was then called Shahin or Shahan.
With the passage of time, this name changed to Zangan and later came to be called Zanjan. In the book named "Hoddodol Aalam" or "limits of the world", (372 AH.), Zanjan has been described as a thriving, flourishing city with strong ramparts.
In the 6th century AH. the Ilkhanans gained power in this territory and the city of Soltanieh was erected and thence known to be the capital of Oljaito. After the decline of the Ilkhanans, Amir Teimoor attacked Iran and reduced this city to Shambles in the year 786 AH. During the reign of Tahmasb Shah Safavid I in the year 930-984 AH. Soltanieh witnessed further decline. But during the reign of Fathali Shah (the Qajar King) built a summer palace in this city.
Today, because of its strategic position both politically and commercially, this city has attracted many immigrants and hereby the increase of population has caused development and increase of city limits.