Semnan province (Persian: استان سمنان, Ostān-e Semnān) is one of the 31 provinces of Iran. It is in the north of the country, with its center and capital in the city of Semnan. The province of Semnan covers an area of 96,816 square kilometers and stretches along the Alborz mountain range, bordering on Kavir desert in its southern parts.

At the National Census of 2006, the population of the province was 570,835 in 159,791 households.^[4] The following census in 2011 counted 631,218 people in 186,114 households.^[5] The province was made part of Region 1 following the division of the provinces into 5 regions, solely for coordination and development purposes, on June 22, 2014.^[1] By the time of the most recent census of 2016, the population had risen to 702,360 in 215,571 households.^[2]

Various ethnic groups with Kurdish, Turkish, Lor, Arab, Baloch and Gilak origins are settled in this province and it is also known as the Island of the Tribes due to the variety of ethnic groups living in the province.^[6]

Semnan province is located on the southern slopes of the Alborz mountain range. The height of the province decreases from north to south until it reaches the desert. The area of this province is 96000 square kilometers and it is 5.6% of the area of Iran.^[7]

This section does not cite any sources. (January 2023)

Semnan can be divided into sixteen sectors from the old days of Avesta. In the Median and Achaemenid times, it accounted for being one of the largest provinces of the empires, and today it roughly corresponds to the borders of the ancient region of Parthia.

During the Islamic era, Semnan was part of the historical region of Gomess or Komesh, and the Silk Road paved its way from the midst of this region. Needless to say, the province was witness to numerous wars.

The Cultural Historical Heritage Organization of Iran lists 470 sites of historical and cultural heritage such as palaces, forts, castles, caravansarais, ab anbars, and badgirs in Semnan. In addition to these, there are various religious and sacred places as well.

The province is divided into two parts: a mountainous region and the plains at the foot of the mountains. The former offers scope for recreational activities as well as being a source for minerals, while the latter encompasses some ancient cities of Iran, including one of the capitals of the ancient Parthian Empire.

The province neighbors Golestan and Mazandaran provinces to the north, North Khorasan province to the northeast, Tehran and Qom provinces to the west, Isfahan province to the south, South Khorasan province to the southeast, and Razavi Khorasan province to the east.

The Semnani languages (known also as Komisenian languages) spoken in the province are a group of Northwestern Iranian languages,^[8] (only 68,700 native speakers in 2019^[9]) of Iran. These languages are accorded only "dialect" status in some sources. Most of the Semnani languages are descendants of the extinct Parthian while Semnani proper has been placed among the Caspian languages descended from the extinct Median.^[10]

There are six Semnani languages named in the literature, these being Semnani, Biyabunaki, Sangsari, Sorkhei, Aftari and Lasgerdi - of which some may only be dialects, although there has been little published concerning the relationships between them.^[11]

Semnani proper (Semnani: سمنی زفون), like other Caspian languages, bears some resemblance to the Old Iranian Median language but was influenced by Parthian in a later process.^[12]

• Bayazid Bastami
• Ashraf Jahangir Semnani
• Darius III
• Dasht-e Kavir
• Fath Ali Shah Qajar
• Hassan Rouhani
• Hecatompylos or Shahr-e Qumis
• Khar Turan National Park
• Mahmud Ahmadinejad
• Manuchehri Damghani
• Parthia
• Rig-e Jenn
• Sangsar (Mahdishahr)
• Seleucids
• Semnani language
• Yadollah Royaee