Peter Dickinson 
Kin [PDF ebook] 

Four children embark on a quest for a new land at the dawn of human history   Africa, two hundred thousand years ago: Suth and Noli were orphaned the night the murderous strangers came, speaking an unfamiliar language and bringing violence to the peaceful Moonhawk tribe. Determined not to die in the desert, Suth and Noli slip away with Ko and Mana. Suth, the eldest, leads them; Noli’s dreams of the future guide them. Ko gives them courage; Mana gives them peace. Their search for a new Good Place, one of food and safety, will take them across the valleys and plains of prehistoric Africa and bring them together as a tribe and as a family.