Many people claim that 'Indian subcontinent' was highly advanced in the past, yet the subcontinent remained fragmented and was repeatedly invaded. If India had a strong civilization, why couldn’t it prevent foreign rule for centuries?

Indian films and mainstream media often glorify historical figures and events. Is Indian history being romanticized to the point that it hinders critical thinking about past mistakes and future improvements?

Note: i am not trying to ask why the Indian subcontinent was so divided in the past. The gist of the question is 'why Indian history has been romanticized & people are oblivious to the truth'. Does it serve any purpose to not tell the masses about the real history?