Ajmer was founded as Ajayameru ("invincible hill") by the Chahamana king Ajaydeva in the 11th century, though some sources cite its founding to the 7th-century king Raja Ajay Pal Chauhan. The city became the capital of the Chauhan dynasty and later saw rule by figures like Prithviraj Chauhan, before falling to the Ghurids after the Second Battle of Tarain in 1192. Under Mughal rule, the Ajmer Sharif Dargah was built, and the city was integrated into the larger Indian Union and modern Rajasthan state in 1956. 

Early history and Chauhan dynasty

• Foundation: The city was founded by the Chahamana king Ajaydeva in the 11th century and named Ajayameru. Some sources attribute its founding to the 7th-century king Raja Ajay Pal Chauhan.
• Chauhan capital: Ajmer became the capital of the Chauhan dynasty, with rulers expanding its territories and repelling invasions.
• Prithviraj Chauhan: The most famous ruler was Prithviraj III, or Prithviraj Chauhan, who defeated Muhammad of Ghor at the First Battle of Tarain but was later defeated and killed by him at the Second Battle of Tarain in 1192.
• Ghurid conquest: Following Prithviraj's defeat, the Ghurids took control of Ajmer. 

Mughal and British eras

• Mughal rule: The Mughal Empire ruled the city, and during this time, the Ajmer Sharif Dargah was built to house the grave of saint Moinuddin Chishti.
• British rule: Ajmer-Merwara was a British district that was eventually merged into the state of Rajasthan in 1949. 

Modern era

• Formation of Rajasthan: The State of Rajasthan was formed on March 30, 1949, incorporating the British district of Ajmer-Merwara.
• Ajmer district: The Ajmer state was merged into Rajasthan on November 1, 1956, and the Kishangarh sub-division was added to form the modern Ajmer district.