At the 2011 census, its population was 373,987. Sanandaj is the twenty-third largest city in Iran.
Until the 17th century it was only a small village, when the governor of the region, Suleyman Khan Ardalan, built (or renovated) a fortress there, known as "SenaDezh", which gave the town its Persian name.
The province of Kurdestan has only one archaeological and anthropological musem. The said is in SalarSeyed Edifice in the city of Sanandaj. Various relics from the region of Kurdestan, as well as other parts of Iran are housed here.