The Horites were an ancient people group who had some dealings with Abraham’s family and the Edomites. The little we know of the Horites comes completely from Scripture.
The Horites are first mentioned in Genesis 14:6. They were defeated by the alliance of kings that also defeated the kings of Sodom and Gomorrah and took Lot and his family captive. The Horites are mentioned as living in Mt. Seir at that time.
The Horites are next mentioned in Genesis 36 where Esau’s descendants are listed. Esau settled in the hill country of Seir, which was also the territory of the descendants of Seir the Horite. It would make sense that, if Seir was the leader of the clan, he would name the mountain area where he and his clan settled as Mt. Seir. The descendants of Seir are given in some detail in verses 20–30, and they are noted as Horite chieftains. Deuteronomy 2:12 tells us that Esau’s descendants displaced and destroyed the Horites. Deuteronomy 2:22 tells us that the Lord destroyed the Horites so that Esau’s descendants could inhabit their territory, also called Edom.
Beyond this, there is no more information about the Horites. They are last mentioned in Deuteronomy 2, except for 1 Chronicles 1, which simply reiterates the information found in the Pentateuch.
While Genesis does provide some detailed information about the descendants of Seir the Horite, we know very little about the larger group of Horites or even if there was a larger group. The etymology of the term Horite may have to do with those who dwell in a “cave” or “hole.” It is possible that the Horites were cave-dwellers or that Seir himself was a cave-dweller so that the name “Seir the Horite” simply means “Seir the cave dweller.” If this is true, then Seir may have been the first of the line, and, as his family/clan grew, the description eventually took the force of a proper noun—much the same way that last names developed in English usage during the Middle Ages.
The fact that the Horites are mentioned in Scripture with no introduction or explanation would indicate that the original hearers/readers of Genesis were familiar with them and the location of Mt. Seir. There are many things in Scripture that we wonder about because we are separated by so many years. For the original audience, the accounts of the Horites would have been rather recent history and required no further explanation.