the Faithful"). On 18 February 1229, the embassy arrived in Delhi with a deed of investiture. Although the Caliphate's status as a pan-Islamic institution had been declining, the Caliph's recognition was seen as a religious and political legitimization of Iltutmish's status as an independent ruler rather than a Ghurid subordinate. The Caliph's recognition was a mere formality, but Iltutmish celebrated it in a big way, by decorating the city of Delhi and honouring his nobles, officers, and slaves. Iltutmish's own court poets eulogize the event, and the 14th century Moroccan traveler Ibn Battuta describes him as the first independent ruler of Delhi. Iltutmish is the only ruler of India to have the Caliph's recognition. Ghiyasuddin Iwaj Shah, the ruler of Bengal defeated by Iltutmish's forces, had earlier assumed the title Nasir Amir al-Mu'minin, but he did so unilaterally without the Caliph's sanction. The Caliph probably saw Iltutmish as an ally against his Khwarazmian rival, which may have prompted him to recognize Iltutmish's authority in India. After the Caliph's recognition, Iltutmish began inscribing the Caliph's name on his coins, including the new silver tanka introduced by him. Other campaigns In March–April 1229, Iltutmish's son Nasiruddin Mahmud, who had been governing Bengal since 1227, died unexpectedly. Taking advantage of this, Malik Balkha Khalji, an officer of Iltutmish, usurped the authority in Bengal. Iltutmish invaded Bengal, and defeated him in 1230. He then appointed Malik Alauddin Jani as the governor of Bengal. Meanwhile, Mangal Deva, the Parihara chief of Gwalior in central India, had declared independence. In 1231, Iltutmish besieged the city, and captured it after 11 months of conflict, on 12 December 1232. After Mangal Deva fled, and Iltutmish left the fort under the charge of his officers Majdul Mulk Ziyauddin. In 1233–1234, Iltutmish placed Gwalior under Malik Nusratuddin Taisi, who was also assigned the iqta's of Sultankot and Bayana, and made in-charge of the military contingents at Kannauj, Mehr, and Mahaban. Shortly after, Taisi attacked the Chandela fort of Kalinjar, and subsequently plundered the area for around 50 days. During this campaign, he acquired a large amount of wealth: Iltutmish's share (one-fifth) of the loot amounted to 2.5 million jitals. While Taisi was returning to Gwalior, the Yajvapala ruler Chahada-deva (called Jahar by Minhaj) ambushed him, but Taisi able to fend off the attack by dividing his army into three contingents. Subsequently, Iltutmish raided the Paramara-controlled cities of Bhilsa and Ujjain