After the death of Balban neither of his successors could face the Mongols boldly. The Khaljis took advantage of the weakness of the successors of Balban and established their own reign.
Lane-poole opines that the slave system was also a contributing factor for the downfall of the slave dynasty. The slaves who were purchased and trained by their masters often tried to degrade their owners.
They always started a tug of war with the princes for power. The enthronement of the slaves of Ghori, one by one, proves that they not only harmed the claims of the princes but also imposed their superiority over them. This tussle between the slaves and the princes adversely affected the administration of Delhi and weakened the Sultanate.
Weakness of Frontier Policy:
Negligence of the frontier is said to be an important factor for the downfall of the so-called slave dynasty. The Mongols and the Khokhars were launching constant attacks during this period and the Sultans like Iltutmish and Balban had to face the brunt of their attacks but the rulers before Balban did not care to secure their frontier against these foreign invaders. Their invasions shook up the roots of the infant Muslim empire.
Balban was the only ruler of the slave dynasty who took steps in this direction and erected forts and appointed powerful soldiers to check the invasion of the foreigners. His son Muhammad was killed in a battle against the Mongols. Thus we see that the weak frontier policy of the slave Sultans proved harmful for both the Sultans and the Sultanate.
Lack of National Feeling and Mix-op of Various Tribes:
During the reign of the Slave dynasty people of various castes had chances to participate in the administration. Afghans, Pathans, Turks, Khaljis etc. Worked on different posts in the administration of the Sultanate. The different tribes were having a competitive spirit against one another. Hence the place of national feeling was blocked by racial feelings and it weakened the Sultanate and made the downfall of the slave rulers inevitable.
Lack of Feeling for People’s Welfare:
As the Sultans of Delhi remained busy in checking the invasions of the foreigners, in expanding their territory and in eliminating the mutual disputes, they could not pay attention-to the welfare of the people.
They did not do anything which could be beneficial to the people of the Delhi Sultanate nor could the people develop affinity with the Sultanate. It ultimately resulted in the downfall of the slave dynasty.