He may be able to conquer northern India, but not Southern India.
he won't be able to conquer india at all
india's allied with china among others (including the turks's friend, russia)
declaring on india would stop asian trade with the europeans indefinitely
considering most of europe is democratic and some of their tenets involve trade routes, this would cripple a lot of nations (including the turks since they're democratic)
so it would be in the best interest of europe to prevent the turks from being stupid
otherwise their treasuries will run dry, they'll fall into debt, and their people will revolt