Planet Of Exile by Ursula K. Le Guin

Set on a distant planet with an exceptionally long orbit, the story explores the complex relationship between two distinct cultures: the indigenous Tevarans and the far-future descendants of Earth, known as the Alterrans, who have been stranded there for generations. As the planet faces the onset of a harsh, decades-long winter, the two groups must overcome deep-seated mistrust and prejudice to unite against the common threat of the nomadic barbarians who threaten their survival. Through themes of cooperation and adaptation, the narrative delves into the challenges of coexistence and the potential for unity in the face of adversity.