Halflings

From the introduction:

The origins of the winterfolk are shrouded in mystery. Sightings of them are so rare in most parts of the world that some doubt they exist at all. Sages debate whether or not they were a distinct people prior to the Great Retreat or if they were once courtfolk or riverfolk halflings who broke away from their kin when the elves departed. It is assumed they were once loyal servants to the elves like the courtfolk, and they still bear a great deal of respect for elves and the elfmarked, though they have little love for the shadow fey.