History : In old times, Tehran was a relatively big village located between the well-known and big city of Rey and Alborz Mountains. Its name mentioned for the first time in the biography of Mohammad-Ebn-e- Hamad known as Abu Abdollah Hafez-e-Tehrani-ye- Razi born in 817. According to the existing historical resources, the village existed before the expansion of Islam and then has gained the Arabic variant name. Later in recent century, coinciding with the Constitutionalism Movement in which several changes made in literature and writing of Persian language, gradually its written form changed into Tehran with “t” used in Persian alphabet and after establishment of The Academy of Persian Language, the term of Tehran with Arabic “t” entirely abolished.
About the name of Tehran there are several different theories but no historical acceptable evidence has been found yet. The similarity of these theories is in the division of the term of Tehran into parts of “Teh” and “Ran”, but the major disagreement occurs in the first part. The term of Ran is usually etermined as a suffix for place and so according to the given meaning to the “Teh”, term of Tehran has different meanings such as “Teh” meaning low land in contrast with Shemiran which means high land or meaning warm land against the Shemiran which means cold place. Moreover, some likened southern slope of Towchal Mountain to the thigh, so called Tehran as the end of the thigh and Shemiran as the head or top of the thigh.
Situation : Tehran city expands in southern foothills of Alborz Mountains and has covered an area in the length of approximately 50 km in 51° 2′ to 51° 36′ east longitude and approximately 30 km between 35° 34′ to 35° 50′ north latitude.
The height of the city in the northern parts is 1800 m, in Tajrish 1548, in Ferdowsi Square about 1200 m, and in the very southern parts reaches to 1050 m from the sea level, Actually Tehran is surrounded between the mountainous area from north and desert from south and under the effect of these two areas, Tehran enjoys variety of climates. Places near to the Alborz Mountain have dry and cold and places near desert have dry and warm weather. Within a period of 30 years between 1966 up to 1996 the average of the maximum temperature Was 22.5° C and the minimum was 11.9° C. The absolute maximum was 43° C, the absolute minimum -15° C, and the average was 17.2° C. The average annual rainfall was 240 mm and the frozen days were 48 days in a year. The features registered for the year 2003 were orderly 23.3°,13.5°, 42.6°, -2.6°, 18.4° C and 240 mm and 12 days.
Population : Population of Tehran at the beginning of the Qajars kingdom was about 15,000 which reached to 150,000 up to 200,000 at the end of Naser-ed- Din shah’s era and at the end of Qajar dynasty it was estimated 250,000 up to 300,000. ln census of Reza shah’s era in 1939 was 540,087. In general censuses of 1956, 1966, 1976, 1986, 1996, 2006 it was orderly 1,512,082; 2,719,730; 4,539,223; 6,042,584; 6,758,845 and 7,797,520.
Tehran City in addition of being the capital of Islamic Republic of lran is also the center of Tehran Province and Township. From administrative divisions point of view, the city is divided into 22 municipal district (mantaqeh) and 112 subdistrict (nahiyeh). The mayor of each district is appointed by the mayor of Tehran. Tehran’s mayor is also selected by the Islamic Council of Tehran.