H. Rider Haggard 
Wisdom’s Daughter (Serapis Classics) [EPUB ebook] 

At the end of She: A History of Adventure, the title character appeared to be killed; but promised to return.
In Ayesha, the second book, the two adventurers from the first novel, Leo and Holly, are inspired to look for She in Thibet.
They discover people who have lived in a hidden mountain since the time of Alexander the Great. They find Ayesha leading the cult of Hes, though they do not recognise her at first. After which, they plan to return to The Flame of Life, in Kor, Africa; but first they have to wait for the paths to clear in the spring…