Answer:
Chahamanas were also known as the Chauhans. The Chahamanas of Sambhar ruled Rajasthan and its adjoining areas. They ruled between the 7th and 11th Centuries C.E. At a later period, the capital of Chahamanas was shifted to Ajmer.
Some of the rulers of Chahamanas were Simharaja (who was the founder of Chauhan dynasty), Vigraharaja Ⅱ , Ajayaraja Ⅱ, Vigraharaja Ⅳ/Visaldev, Prithviraj Ⅲ, Hari-raja.
Ajmer was conquered by Qutub-ud-din Aibak by defeating Hari-raja. The last stronghold of Chauhan power was removed by Alauddin Khilji. He captured Ranthambore in 1301 C.E.
Chittor was captured by Vigraharaja Ⅱ. The most famous of all Chauhan Kings was Prithviraj Chauhan. Mohammad Ghori was defeated by Prithviraj Chauhan in the First Battle of Tarain. However, he was defeated in the second battle of Tarain.