At the time of the 2006 National Census, the city's population was 11,083 in 2,896 households.[6] The following census in 2011 counted 11,939 people in 3,470 households.[7] The 2016 census measured the population of the city as 12,989 people in 4,048 households.[2]
In literature
The 14th-century author Hamdallah Mustawfi mentioned Sa'in Qal'eh in his Nuzhat al-Qulub: he referred to "the village called Quhūd, which the Mongols call Sāin Qal'ah, and which is the chief of all those neighboring hamlets".[8] He also wrote that it was close to the castle of Sarjahan.[8]
^Sain Qaleh can be found at GEOnet Names Server, at this link, by opening the Advanced Search box, entering "-3081938" in the "Unique Feature Id" form, and clicking on "Search Database".
^Habibi, Hassan (18 May 1390) [Approved 8 May 1376]. Changes in national divisions in Gilan and Mazandaran provinces. rc.majlis.ir (Report) (in Persian). Ministry of the Interior, Board of Ministers. Proposal 1.4.42.5543. Archived from the original on 9 August 2011. Retrieved 17 December 2023 – via Islamic Parliament Research Center.