Quranic writ controlled and governed the administration system of Delhi Sultanate. The Caliph was the cardinal sovereign, with all the Muslim kings as subordinates. The Sultan being the head of the administration had the key role in all types of administrations.
The Sultan’s power was based on two things – religion and military. He has to enforce and interpret the Quranic law. Ala-ud-din Khilji and Muhammad-Bin-Tughlaq had violated the Quranic laws but nobody antagonised them. They cannot be removed from the throne easily, but only through civil war. The Sultans were also the religious head of the Muslims.
The Sultan was the commander-in-chief of the army, and had all powers of the State in his hand.
The Sultanate government was a centralized entity having democratic nature of an Islamic State. The Sultan used to appoint numerous ministers. At the time of slave dynasty, there were four ministers: the Wazir, the Ariz-i-mamalik, the diwan-i-insha, and the diwan-i-rasalat. Sometimes there was also the post of naib-i-mamalik, who was next only to the Sultan. Usually naib acted as Deputy Sultan, but when the Sultan became weak, the naib assumed the power. Also the posts of Sadr-us-Sudur and Diwan-i-qaza were given the status of ministers. Hence, there were six ministers during the peak time of Sultanate administration.
Wazir or the Prime Minister had great authority, and all the officers were appointed by him only. He was the advisor of the Sultan in the administrative affairs. He was the head of the finance department, by regulating the revenue settlement, fixing the taxes, and controlling the expense of the empire. His office was known as the diwan-i-wazarat.
Diwan-i-ariz was next to the Wazir, and was the controller general of the military. He recruited troops and maintain the army men and horses.
Diwan-i-insha was in-charge of the royal correspondence, and ranked third in the administrative structure. His assistants used to make all correspondence, even of the confidential matters.
Diwan-i-risalat or the minister of foreign affairs was in charge of dealing with diplomatic correspondences and the ambassadors. He was an important officer as all the Sultans were curious to maintain diplomatic relations with the Central Asian powers.
Sadr-us-Sudur or the minister of the department of religion, used to enforce the Islamic norms and to monitor whether the Muslims strictly follow those regulations in their day-to-day lives. He also expended the money in charity and rewarded the Muslim scholars.
Diwan-i-Qaza or the head of the judicial department, managed the justice in the empire.
Amongst all the ministers, only the Wazir relished the higher status and privileges. No council of ministers was available. The Sultans had the privilege to appoint and dismiss any of the ministers. There was a circle of non-official advisors of the Sultan known as Majlis-i-Khalwat. Some other posts were existing like barid–i–mamalik (head of the intelligence and posts department), diwan–i–amirkohi (department of agriculture), diwan–i–mustakhraj, diwan–i-¬khairat (department of charity), diwan–i–istihqak (department of pension), Sar–i–jandar (Chief of the royal bodyguards) and diwan-i-bandagan (chief of the slaves).
Therefore, the Delhi Sultanate was never branched into consistent provinces with uniform administrative system. This Sultanate was a centralized monarchy. None of the Sultans of Delhi thought of reorganizing the provinces on a uniform basis.