Tarr (Queen of Swords, 1997, etc.) usually grinds out two huge historicals a year based on medieval and ancient history. Here, though, she takes a giant leap back into Neolithic times and a mythic Old Europe to focus on the majestic White Mare--the Great Goddess Epona incarnate--and on ancient equestrian practices among nomads, as well as on goddess worship. The White Mare's daughter is the beautiful priestess Sarama, who leads a nomadic warrior band on a quest for a metropolis masterminded by females; at one point, she nearly exhausts herself in crossing a magically vast forest. The story is based on the Kurgan invasion of the Cucutemi peoples in the area south of what is now Kiev-and yet unlike Tarr's earlier historicals, which adhere to known events, the fantasy this time flies more freely. Whether or not, for instance, there actually were cities in Old Europe remains in question among historians, but not for Tarr, who finds the stuff of epic much livelier here as she's cut loose from her usually lackluster limning of figures like Alexander the Great, Akhenaten, and Hatshepsut. The author's fans (old and new) should flock to what the publisher hopes will be her breakthrough this time to a wider public.