I'm sorry if this doesn't reach you because the post got deleted accidentally. as far as i know, the migration of central asia and aryan invasion theory is debatable because there's proof against it. i agree to some point of yours and hence would award delta. however, i really don't think the religions practised were obscure.

let me cite an example, creamation of dead bodies and then throwing ashes into Indus was a fairly common practice because it was believed that mother Indus will lead them to afterlife. it's the same practice of final rites that's performed by hindus. you can find gods lile Indra and Shiva that essentially forms the backbone of hindu mythology in IVC. to check Shiva's connection with Indus, you just need to look at source of Indus i.e Mansarovar lake and mount Kailash. ∆