after spending some really long hours on the net i found this
One of Prithvi Raj's brothers, Hemraj, besieged the Muslim-held fort of Ranthambhore which was garrisoned by Aibak's commander Kiwan-ul-Mulk. In Ajmer, some Chauhan noblemen seized power from Prithvi Raj's son who had accepted Ghori tutelage bringing shame to his brave and patriotic father's name and house. This shows how dynamic Hinduism never tolerated weak and unpatriotic rulers. Prithvi Raj's son had to flee from Ajmer. Aibak left at the head of Ghori's Muslim desperadoes and re-established Muslim power in Ranthambhore and Ajmer. Prithvi Raj's son was once more restored to his tutelage in Ajmer but the brave Hemraj was still unvanquished. The Dor Rajputs of Baran now reasserted their independence and Aibak had to rush his army across the Yamuna. It was at this time that he captured what has since come to be called Aligarh.