One title that I am constantly raving about is Wolf Brother and the subsequent Spirit Walker by Michelle Paver. Set 6000 years ago, it has an immediate primitive feel about it and draws the reader in quickly. Torak, the chief protagonist of the stories, which by the way is in six parts, with only the first 2 books published so far, is both an admirable character and yet one that endears himself to us. I won't give a synopsis of the story so as to entice people to read it. But what I can say is that Paver has done a great deal of research to maintain the authenticity of the time frame, because that gives the story it's raw edge and a strong feel of how the ancients used to live. There is also an inextricable link between the spirit world and the real world so much so that that the two are sometimes inseparable. The various characters in the story are well-drawn out and by the second book, Spirit Walker, the characters grow through the challenges they face but at the same time more questions are posed which I believe the subsequent books will reveal.
Definitely a book worth your time.