La Tierra Multicolor by Julian May

Set in a distant future where humanity has developed the ability to travel through time, the story follows a group of misfit exiles who escape their oppressive society by journeying back to Earth's Pliocene epoch. There, they encounter an alien race with advanced technology and psychic abilities, leading to a clash of cultures and a struggle for power. As the exiles navigate this vibrant and dangerous world, they must confront their own pasts and forge new alliances to survive in a land where the past and future collide.