Spreading Islam was only collateral ( pyar,ke side effects ) and an excuse to greed of Invaders to plunder,loot,massacre in India.
They converted Indians to Islam and married with Hindu Maharajas for political and military alliances and to protect their own interests and kingdoms.
It was as much of a subterfuge,as USA first attacking Iraq for WMD ,then after failing to find it,tried to justify it on grounds of freeing Iraqi people .
USA has sure freed Iraqis of their homes,family members and body parts. ( America ke side effects )