Ayesha, The Return of She (Barnes & Noble Digital Library‪)‬

This sequel to Haggard's classic adventure fantasy, She (1887) was published in 1905.  Convinced that Ayesha, "She Who Must Be Obeyed," did not die in Africa, Leo Vincey and Horace Holly track her to Tibet, where they find themselves plunged into a timeless conflict, fought throughout history by means of reincarnation.