Men from the land of Telmar, far beyond the Western Mountains of Narnia, in the book Prince Caspian by C.S. Lewis (one of The Chronicles of Narnia).
The ancestors of the Telmarines came from our world. They were a shipload of pirates driven by storm onto a South Sea island. Six of them and their native wives were driven away from the rest of the group. They took shelter in a cave that proved a magical gateway to the unpeopled land of Telmar. Their decendents became a proud people; when a famine fell on the land King Caspian the First invaded and conquered Narnia.
Over the years the Telmarine kings expunged all historical records of Narnia's earlier days -- even of the existence of the Talking Beasts who were driven into hiding. The old stories of Aslan, Narnia's Lord who came from over the sea, were only dimly remembered; Telmarines nevertheless were afraid of the sea and allowed the art of seafaring to die.
When Caspian the Tenth overthrew his cruel uncle King Miraz the Usurper, Aslan gave the Telmarines a choice: stay in Narnia as friends of the Talking Beasts or return to that South Sea island, now uninhabited. Aslan created, then closed, the gateway that brought those who did not stay back into our world. The remaining Kings of Narnia were of Telmarine lineage.