Gerald Brefka 
The First Horse People [EPUB ebook] 

The Yumnayas were the ancestors to all the first horse people. The Botai were the first horse people. The Sarmatians were the second horse people. Of all these first tribes, they were the most European-looking with blond hair and blue eyes, even though they all had the same root language given by the Yamnayas. The third was probably the Androvo tribe but would not be heard from in the west until they found the fastest horses in the world in Siberia. The true menace was the fourth tribe, the Scythians, the number 1 competition to the Sarmatians.
This is the story of how these tribes interacted with one another. It’s a story with action from beginning to end.