Originally Posted by windsock

Nietzsche wrote the ideas of pre-Socratic philosophers in Ancient Greece in regards to their kind of proto-pessimism. He specifically pointed to Anaximander (who predates Plato quite a bit iirc) as a "true pessimist", though like I said before I'm not well-read enough in Greek philosophy to know the subtle nuances between their brand and present-day pessimist thought.

As for the Vedics, I'm not very familiar with Vedic-era literature other than some cursory knowledge of the Rigveda and Kautilya's Arthashastra (which I believe is Vedic era but I could be wrong), so I honestly don't know how much influence they had on Schopenhauer. If you'd like to enlighten me on that though I'd very much like the knowledge.