I'm watching HBOs Rome which is supposed to be a far more accurate depiction of Rome compared to most other media portraying it, and in a scene where the character Atia is sacrificing a bull to the gods, her and an altar are beneath where the bulls throat is cut and she is drenched in its blood. Is this a real thing they did? What did they believe the benefit of this was? Was it to a specific god or gods?
I think this comment from our own /u/Tiako should set you straight. It's not very long but...frankly there's not much to be said there. Rome is "a far more accurate depiction of Rome compared to most other media portraying it," I suppose, as you say, but that's not a high bar to clear. Rome is a sword-and-sandals flick, and the usual tired and ridiculous cliches of sword-and-sandals flicks since the inception of the form are central to the show. Including, naturally, those weird super spoopy pseudo-oriental religious rituals which were oh so strange (thank God we're enlightened now) and which the producers totally didn't just make up