White mare's daughter

"An epic tale of adventure and romance follows a beautiful, headstrong young priestess named Samara, whose white horse is the incarnation of a goddess on Earth and whose fateful clash with a city where women still rule changes the course of history."@en
"In a time before history, in a land of legend, where wild horsemen wage endless war across a sea of grass, the last descendant of the White Mare's servants follows a sacred vision beyond the edge of the world. There she finds a land ruled by women, whose people have no word for war. But the horsemen are coming. The White Mare's daughter must try to stop them, and both save and change the world."@en
"A feminist novel on a clash of two societies, one of warriors, the other ruled by women where war is unknown. Set in 4,500 BC in what is now Ukraine, the story features a heroine from the warrior tribe and a hero from the matriarchal one."