Final answer:
The Delhi Sultanate fought unsuccessfully to defend northern India against Mahmud and his successors.
Step-by-step explanation:
The Delhi Sultanate fought unsuccessfully to defend northern India against Mahmud and his successors. The Delhi Sultanate was a Muslim state that dominated much of northern India between 1206 and 1526. They were one of the few states that successfully defended themselves against the Mongols, but ultimately they were weakened by uprisings and overthrown.