I believe that hinduism is just another "ism" which is by definition man made. The best definition of hindu is exactly what you have stated, "people living on the east side of the sindu river". Such a definition is inherently geographical and "racial". I have given up the title of "hindu" because such titles are exactly what the vedic scripture teach us to abandon. I am not a hindu, i am not indian, i'm not white, i'm not mexican, i'm not catholic, i'm not muslim, i am a soul. This is the true teachings of the bhagavad gita. The fact that Prabhupada stated he is not a hindu only serves to show us how wise he was.