Correct, however the ghaharvads and chandellas resisted them for near a century.he reason is geography. Northern plains are fertile and can support big population and big armies. But once the dominant military power is defeated, there is no scope for guerrilla warfare and resistance against a powerful cavalry, there is no running for the hills as there are no hills.
the senas defeated muslims in bengal time and again and that too in the plains.
people do not realize the size of turkish cavalry, it was in tens of thousands which made it difficult for people other than rajputs to resist them.