Currently the way Hindiusm is seen, these topics are considered as a part.
Aryan Invasion : We have related text about Aryans but none of them depict anything related to Invasion, making Aryan Invasion a off topic, but to sincere note, this is still a healthy part of discussion in many societies which consider it as a part of Hinduism.
Dowry : Again there is no written text about dowry in the text books, it was just a surprise parents used to offer their girl child, which became a fellowship and converted to dowry again a non legitimate off topic discussion.
Sati : We have textures about Devi Sati, but nothing about Sati practice, again a off topic, yet a part of discussion in most societies.
Similarly their are numerous topics even caste system, which being not the part of Hinduism are attached to it, either by non-hindus, anti-hindus and some pro-hindus too.
Currently I see two division of Hinduism, a hinduism which acutally existed in the form of Sanatan Dharma pure and eternal, and Hinduism added by some blind-scholars, pride-prejudicers and stupid-fellowshipers.
As due to those empty vessels piled up, I think these can only be removed by conciousness. Can I add question relate to these and similar topics?
