Some people say the Ramayana took place about twenty thousand years ago whereas Krishna was born on earth about five thousand years ago. But Krishna belongs to the previous yuga (age) and Rama to the yuga before that and these yugas last for hundreds of thousands of years. So it seems the Ramayana must have taken place alot longer ago. Also the people in the Ramayana are said to have been around 16 feet tall and there was a monkey like race and also bears who could talk, so it seems this would have to be a lot longer than 20 thousand years ago. A friend and I asked an older Hindu scholar about this once and he told us to focus on what was important and not to waste time on such things. If however anyones got any information I'd be interested.