"Planet of Exile" by Ursula Le Guinn

Usually taken to be the first book to be written in the 'Hainish Cycle' by Ursula Le Guinn, the action of the book happens towards the middle of the period covered by the eight (so far) novels within the cycle. Located on the third planet of the Gamma Draconis star, the book depicts the interaction and mutual characterization of two hominid groups on the planet. One group are the native High Intelligent Life Forms (HILFs), who have inhabited the planet for millenniums and are well adapted to the 60-earth-year orbit of the planet around the star with nomadic lifestyles and neolitic level of technology. The other group are the Alterrans, a mix-breed of Terrans from Earth and another species, which arrived on the planed 600 years ago (10 local years) to try to include the planet in the "League of Worlds".

However the League entered heightened state of war at the time of the Landing and the starship that brought them had to go back, tacking with it the 'ansible' and instantaneous communication device regardless of spatial parameters, and pretty much all advanced technology. The people that remained on the planet lost most of their advanced technology, some through 'cargo laws' and some through ignorance, and although living in real houses and cities, are lowered to the level of hunting with spears and knives, as the locals do.

The locals have some strange customs, like never looking directly in the face of another person, and consider the Alterrans and inferior breed, non-humans, which feeling is reciprocated by the Alterrans themselves, however they are much weakened numerically and because of their abandonment of their original superior technology. The Alterrans also have breeding problems; they have very few children and are slowly disappearing. This is exacerbated by the fact that the locals (Tevarans) and the colonists (Farborns) cannot interbreed, though they theoretically have a common ancestor in the people from Hain, which colonized most of the known universe with their own genetic code.

The Alterrans and the HILFs are forced to unite, just before the oncoming of the 15-year long winter, when a barbarian horde from the North comes and destroys the Tevaran city and tries to do the same with the Alterran one as well. The united people, or what is left of them, succeed in defending the new city and become more friendly towards each other, the leader of the Alterrans, Jacob, taking a HILF wife, Rolery. During the battles the Alterran doctor realizes that their bodies started to adapt to the local conditions to the point where they can be infected by local bacteria. This leads him to think that Alterran-HILF breeding would soon be possible and a new race will emerge.

Towards the end of the book, after successfully defending the city, Jacob realizes that they are no more on a planet of exile, but that the planet has become their home too.