In fact, he could get this office because of the disharmony among the members of the group of forty Turkish slaves. During the reign of Alauddin Masud’Shah, Muhazabuddin, the Wazir, continued on his post. However, the Turkish nobles remained working on the remaining important posts.
Muhazabuddin tried to destroy the group of Turkish nobles but he did not succeed in his mission. On the contrary, the Wazir himself had to forgo his office. Nizamuddin Abu Bakr was appointed on the post of Wazir and Balban was assigned the office of Ainir-i-Hajib.
Balban was not a very senior member of the group of forty out he told get the significant post of Amir-i-Hajib by his virtues, worth and cleverness. Later on, as leader of the group, he occupied the powers and the reins of the government.
Masud Shah ruled peacefully for four years. No doubt, some disturbances took place in the east and the north-west and Tughan Khan, the Governor of Bengal, endeavoured to challenge the authority of the Delhi Sultanate. He achieved victory over Bihar and invaded Avadh and a prolonged conflict took place with Tamar Khan, the Governor of Avadh.
The Governors of Multan and Uchh tried to establish their independence but they continued to rule under the authority of Masud Shah due to the fear of Mongols. In fact, during the reign of Masud Shah, Balban gathered all the powers, of the state.
The mutual jealousies prevalent among the Turkish slave officers of Iltutmish also gave Balban opportunities to amass power. When he felt confident that his position was quite sound, he conspired against Alauddin Masud Shah and deposed him from the throne in June 1246 a.d.
Again because of mutual jealousies, the Turkish nobles failed to be unanimous on the installation of one of them and, ultimately, a grandson of Iltutmish was selected for enthronement.
Signs of disintegration began to be visible, although slow, in the reign of Alauddin Masud Shah, The power of the group of forty was still at its zenith and the Sultans were installed and removed from the throne according to their sweet will. They had become the king-makers in the real sense of the term.