Ajmer was established in the early seventh century by Ajaipal Chauhan. Ajaipal Chauhan constructed a tall fort here and named the place Ajaimeru means invincible hill. Here he built India,s first hill fort Taragah. Ajmer was a Chauhan's Stronghold till 1194. The Only remains of their times are the fort and the beautiful Anasagar lake built in 1150 by Anaji. The legendary Prithviraj, last of the Chauhans, is the inspiration for many heroic ballads sung even today in the villages of Rajasthan.

It was during the regime of Prithviraj, in 1191, that Muhammad of Ghori invaded India. Prithviraj died fighting the sultan's army, and with the establishment of the Sultanate in Delhi, a new era began.

Ajmer remained under the Sultanate till 1326. Thereafter, it became a bone of contention between the Sultans of Delhi, the Ranas of Mewar, the Rathors of Marwar and the Sultans of Gujarat. Peace was restored with the accession of Akbar to the Mughal throne in 1556. He made Ajmer a full fledged province and the base for his operations in Rajputana.

He fortified the city, but only parts of the 4045-yard (3735-m) long wall remain.

His palace, the Daulat Khana, houses the Government Museum.Akbar's son, Jahangir, lived in Ajmer from 1613 to 1616. His palace, the Daulat Bagh, is now in ruins. The celebrated English ambassador during to the Mughal court, Sir Thomas Roe, was received here by the emperor.

During the course of his extended stay, Roe met the emperor several times and showered him with gifts varying from maps to a coach. But he failed to conclude a commercial treaty between England and the Mughal empire.

In 1659 a battle was fought in Ajmer between the Mughal princes, Aurangzeb and Dara Sukoh, during which Taragarh was greatly damaged. In the first half of the 18th century, Ajmer was affected by the political chaos in Delhi. At times it was the Rathors who reigned here, at others the emperors of Delhi.

In 1755, the situation became more complex with the involvement of the Marathas.

In 1818, finally the Marathas ceded Ajmer to Sir David Ochterlony and, as part of the British empire, it remained under the care of successive superintendents.

In 1947, with the reorganization of the princely states Ajmer became a part of Rajasthan.