Alice C. Linsley
Trees served as border markers for the ancient Hebrew. Terebinth trees marked the northern and southern boundaries of Abraham's territory between Hebron and Beersheba. Sarah, Abraham's half-sister wife, resided in Hebron, and Abraham's cousin-wife resided in Beersheba. The wives' settlements marked the northern and southern boundaries of Abraham's territory in ancient Edom.
Hebron and Beersheba (where Keturah lived) are in Idumea (Edom).
One of the rulers of Edom was Seir the Horite. He was a contemporary of Esau the Elder. He married Adah. Esau the Younger is described as red and hairy. He married Oholibamah.
After offering Isaac at Mount Moriah, Abraham didn’t return to Sarah in Hebron, but instead went to live in Beersheba with Keturah (Genesis 22:19). There he had built an altar and planted a terebinth. A terebinth marked the northern end of Abraham's territory (Gen. 12:6) and after Abraham formed a treaty with Abimelech, he planted a terebinth at the southern end of his territory (Gen. 21:22-34).
People often were buried under oaks and terebinths (Gen. 35:8; I Chronicles 10:12). This helped to ensure that the boundaries were observed since people stayed away from burial grounds, fearing the spirits of the dead.
Related reading: Edom and the Horites; Trees of the Bible; The Trees of Prophets; What Happened to the Cedars of Lebanon?