The story of the Caribou Clan has romance, warfare, and overwhelming displays of nature's power in falling stars, a tornado, a brilliant nova, and an earthquake, in an unforgiving, difficult desert environment from which the Clan flees, walking ever eastward until they find that the Pacific Ocean is bordered by a wide green terrace where sea levels have fallen dramatically due to the mantle of glacial ice to the north.
Taga, the youngest son of the powerful Tzan, has fled into exile with Maa. When a tornado brings devastation to the Caribou Clan, Taga, with wife Maa, son Tuit, and shaman uncle Tlan trek to help their kinsmen, finding that Tzan is dead. The wise old shaman becomes leader of the Caribou Clan, instituting a creative, mild guidance as he shares his enormous learning and the group prospers. Tlan marries Elar, who teaches neatness and harmony to the women.
A nomadic tribe of ugly, dirty thieves becomes the deadly enemy. Taga, now the leader, wages war to decimate the Urkluk Clan. Afterwards his wife awakens his feelings of guilt over killing the women and children of the Urkluks. A long-lost son of the Tzan returns, but this charming, intelligent man is really an illicit son of Tlan and the Tzan's fourth wife. Instead of finding a woman of his own, Alun falls in love with Maa, the perfect mother and wife, bringing her deep inner conflict as the Caribou Clan begins its long journey over mountains to the east; they learn to depend upon animals other than their beloved caribou. As they near the coast, they meet the water people, who show them the advantages of rafts and seafood and who enable them to reach the shores of the Pacific Ocean, where they turn northeastward.