Actually, the dating of the epic Ramayana is controversial. Recent Vedic scholars, following astonomical clues (the positions of particular stars and planets mentioned during battles in the Ramayana) place the historical age at around 7500 BCE.
The Vanar or Monkey Army, it has been theorized, were actually the darker-skinned locals of Dravidian descent, the same folks who built the Shore temples at Mahabalipuram thousands of years later. What is interesting is that Hindu Scriptures insist on both the Ramayana and Mahabharata as historical fact, not myth (as the majority of Hindu mythology is freely acknowledged to be.) Just as the Bhagavad Gita is a small sliver of the Mahabharta, Ramayana (miracles notwithstanding) is acknowledged by the majority of Hindus to have a historical basis.
This more recent dating dovetails nicely with the ice-age theory of Sunsword. I couldn't begin to speculate on the origin of Adam's Bridge, but the prospect of a proper investigation is fascinating..