The Plains of Passage is the fourth of the Earth's Children series, and, like The Valley of Horses (1982) is a travel novel. It does include more than nature scenes: Ayla and Jondalar encounter several communities of Cro-Magnon people and even some Neanderthals. It thus has a busier and less characteroriented plot than The Clan of the Cave Bear (1980) and The Mammoth Hunters.

The Clan of the Cave Bear continues to be the strongest novel of the series. In it, the creation of the prehistoric world was fresh and interesting; the story focused on three main characters; Ayla as a girl growing up showed some character development; and the sex in the novel was integral to the story. The Plains of Passage presents new landscapes and new peoples, but its themes and characters wear thin, the sex is overdone, and the source of conflict in the novel...