But even Wikipedia estimates that Gilgamesh himself lived between 2500 BC and 2000 BC. The authentic date of an existing record of the Gilgamesh epic is only from 700 BC. The Mahabharata on the other hand, is from at least 5000 BC. The Ramayana is even older, from 7000 BC.
When modern human species evolved approximately 200,000 years ago, it should not be so far fetched to imagine that advanced civilizations existed 10,000 years ago?
A google search provides many good resources & links that I will just fill up my comment to provide. These resources have documented many many proofs, events more than 3000 years ago cannot be treated the same as events 500 or even 1000 years ago, because the archeological remains would not survive that long unfortunately. Please try this: https://www.google.com/search?q=dating+the+ramayana
I think the research done by PN Oak & Dr. Koenraad Elst would be most pertinent. I am assuming that you are not limited or prejudiced by the timelines provided in the bible or something else.