in 1234–35. Iltutmish's army occupied Bhilsa, and destroyed a temple whose construction - according to Minhaj - had taken three hundred years. At Ujjain, his forces damaged the Mahakaleshwar temple and obtained rich plunder, but made little effort to annex the Paramara territory. The jyotirlinga at the site was dismantled and believed to be thrown into a nearby 'Kotiteerth Kunda' (a pond neighboring the temple) with the Jaladhari (a structure supporting the Lingam) stolen during the invasion. By 1229–1230, the north-western boundary of Iltutmish's kingdom appears to have extended up to the Jhelum River, as Nasawi states that he controlled the area "up to the neighbourhood of the gates of Kashmir". During this period, Iltutmish invaded the territories controlled by the Khwarazmian subordinate Ozbeg-bei, in present-day Pakistan. Ozbeg-bei fled to the Khwarazmian ruler Jalal-ad-Din in Iraq, while Other local commanders - including Hasan Qarluq - surrendered to Iltutmish. Qarluq later changed his allegiance to the Mongols. During his last days, in 1235–1236, Iltutmish is known to have aborted a campaign in the Binban area: this campaign was probably directed against Qarluq. Hammira-mada-mardana, a Sanskrit play by Jayasimha Suri, mentions that a mlechchha (foreigner) called Milachchhrikara invaded Gujarat during the Chaulukya reign. The Chaulukya minister Vastupala used diplomatic tactics to create many difficulties for the invader, who was ultimately defeated by the general Viradhavala. Some historians have identified Milachchhrikara with Iltutmish, thus theorizing that Iltutmish unsuccessfully tried to invade Gujarat. However, others have dismissed this identification as inaccurate. Death and succession In 1236, Iltutmish fell ill during a march towards Qarluq's stronghold of Bamyan, and returned to Delhi on 20 April, at the time chosen by his astrologers. He died in Delhi shortly after, on 30 April 1236. He was buried in the Qutb complex in Mehrauli. The death of Iltutmish was followed by years of political instability at Delhi. During this period, four descendants of Iltutmish were put on the throne and murdered. In the 1220s, Iltutmish had groomed his eldest son Malikus Sa'id Nasiruddin Mahmud as his successor, but Nasiruddin died unexpectedly in 1229. While leaving for his Gwalior campaign in 1231, Iltutmish had left Delhi's administration to his daughter Razia. Her effective administration prompted him to declare her as his heir apparent in 1231, upon his return from Gwalior. However, shortly before his death, Iltutmish seems to have chosen his surviving eldest son Ruknuddin Firuz as his successor.