Iltutmish himself led an army against Jalal ad-Din. Only the vanguards of the two armies clashed, and the two rulers withdrew after exchanging friendly messages. Meanwhile, Qabacha - who had earlier accepted Jalal ad-Din's suzerainty - rebelled against him, and this conflict kept Jalal ad-Din busy. Jalal-ad-Din carried out some more campaigns in India, including a raid in Gujarat, but none against Iltutmish. He left the Indian frontier in 1223–1224; according to his biographer Shihab al-Din Muhammad al-Nasawi, he did so because he received the news that Iltutmish, Qabacha, and several Hindu chiefs ("rais and thakurs") had formed an alliance against him. The Mongols also maintained a presence in the region: for example, Genghis Khan's general besieged Qabacha in Multan in 1224, before retreating because of hot weather. Until Genghis Khan's death in 1227, Iltutmish chose not to get involved in the politics of the Indus valley region to avoid a potential conflict with the Mongols. Territorial expansion Eastern India and Rajasthan Iltutmish's predecessor Aibak had appointed Ali Mardan Khalji as the governor of Sultanate's territories in eastern India. After Aibak's death, the region became independent, with Lakhnauti as its capital, and Ali Mardan's successor Ghiyasuddin Iwaj Shah (alias Husamuddin Iwaz Khalji) styled himself as a sovereign Sultan. While Iltutmish was busy at the north-western frontier of his empire, Ghiyasuddin captured parts of present-day Bihar, and also extracted tribute from the smaller states of Jajnagar, Tirhut, Bang (in Bengal region), and Kamrup. Iltutmish's forces captured Bihar in the 1210s, and invaded Bengal in 1225. Ghiyasuddin led an army to check Iltutmish's advance, but then decided to avoid a conflict by paying him tribute and accepting his suzerainty. Iltutmish accepted the offer, and returned to Delhi after appointing Malik Jani as the governor of Bihar. In 1226, Iltutmish captured the Ranthambore Fort, which was reputed to be impregnable. The next year, he captured the fort of Mandore, also in present-day Rajasthan. Meanwhile, in eastern India, Ghiyasuddin re-asserted his independence and occupied Bihar. In 1227, Iltutmish directed his son Nasiruddin Mahmud, who held the iqta' of neighbouring Awadh region at this time, to invade Bengal while Ghiyasuddin was away on a plundering campaign in Kamrup. Nasiruddin captured his capital Lakhnauti, and defeated and executed him on his return to Bengal. Following this conquest, the coinage in the Bengal region was issued in the name of Iltutmish, and the khutba in Lakhnauti was