In 1191, he invaded the territory of Prithviraj III of Ajmer, who ruled his territory from Delhi to Ajmer in present-day Rajasthan, but was defeated at the First Battle of Tarain. The following year, Mu'izz al-Din assembled 120,000 horsemen and once again invaded India. Mu'izz al-Din's army met Prithviraj's army again at Tarain, and this time Mu'izz al-Din won; Govindraj was slain, Prithviraj executed and Mu'izz al-Din advanced onto Delhi. Within a year, Mu'izz al-Din controlled North-Western Rajasthan and Northern Ganges-Yamuna Doab. After these victories in India, and Mu'izz al-Din's establishment Delhi as the capital of his Indian provinces, Multan was also incorporated as a major part of his empire. Mu'izz al-Din then returned east to Ghazni to deal with the threat on his eastern frontiers from the Turks of the Khwarizmian Empire, whiles his armies continued to advance through Northern India, raiding as far as Bengal.