Alauddin khilji was able to conqure the world
Answers
Brutality & Strategic depth. That was pretty much the entire reason. IIRC I'd answered something similar long back. Anyway...
The Delhi Sultanate pretty outclassed the Mongols in every possible way: Economic, Military, and Administrative. In terms of logistical ability & mobility, the Mongols were superior- but with the strategic depth used by the Khaljis as well as their exceptional bureaucracy, they were able to counter & stem the Mongol advance at every possible point.
The Mongols were a national militia; most possessed multiple horses &, after the conquest of China, good weapons as well- but they were for most part, simply not the equal of the older, taller, heavier, better armoured, and better equipped Indian professional soldier. In addition, Indian troops had the advantage of better bureaucracy & logistical links- especially important because their cavalry was grain-fed whereas the Mongol cavalry had to be grass-fed; grass that often never existed at all.
None of the politicians and activists accusing the film maker of denigrating the honour of the Rajput queen of Chittor, Padmini, and glorifying the “Muslim conqueror Khilji” has even seen the film yet.
Much of the controversy is fuelled by ill-feeling towards Khilji, based on the fact that he was an oppressive ruler to his subjects, who were mostly Hindu. So the possibility of romance – or even unrequited love – between a Muslim “villain” and a Hindu queen being depicted on screen, even as a fantasy, as has been rumoured, infuriates Hindu right-wing groups.
What is not well-known, however, is that Khilji, for all his faults, saved India from a fate much worse than even his own oppressive rule – that of the murderous Mongols, who tried to invade the Indian subcontinent six times during his reign as the sultan of Delhi, and failed miserably, thanks to his brilliance as a general, the quality, discipline, and bravery of his army and its commanders, and their superior military tactics.