Tehran, is the latest and the largest capital city in the 5000-year history of Persia, as Iran was called by many people in the West before 1935. The original settlement of Tehran, north of the ancient city of Rey, may have been founded as early as the 4th century. By the early 13th century it was a small village. In 1221 invading Mongols led by Genghis Khan destroyed Rey, but Tehran survived and grew slowly in the following centuries. During the reign of the Safavid shah Tahmasp (1524-1576) a wall and four watchtowers were built around the city, and by the early 17th century Tehran had about 3000 houses. In the 1720s Afghan invaders attacked Tehran.The town defeated the initial Afghan force but fell to the main Afghan army and suffered tremendously under their occupation from 1723 to 1729. Nadir Shah freed Tehran in 1729.
In 1788 Agha Mohammad Khan, founder of the Qajar dynasty, made Tehran his capital, inaugurating the modern history of Tehran. At this time Tehran’s population was estimated to be 15,000. Under the Qajar dynasty (1786-1925), Tehran grew in population and size, and new administrative buildings, palaces, mosques, and garrisons were constructed.