I believe its because religion is more of a deep common subject talked about compared to rationalist approaches of greek and Confucian philosphy
They have different beliefs Muslim pray to one true god and once you die you are judged by what good and bad things you have done in your life and that will determine where you go while Hindus believe that once you die you can come back to life with reincarnation and they have more then one god
I believe it’s improved transportation