Keturah was a Hebrew Wife

 

Hebron and Beersheba are shown on this map.

Dr. Alice C. Linsley

All Hebrew wives were close kin to their husbands because the Hebrew ruler-priests practiced caste endogamy. Some Hebrew wives were their husband's half-sisters. That is the case with Sarah. She and Abraham had the same father but different mothers. Terah had two wives, as did many of his Hebrew forefathers. It was common for high-ranking Hebrew chiefs to have two wives. 

The half-sister was the bride of the ruler's youth, and the cousin bride was the wife of the ruler's later years. The cousin wife was sought before the Hebrew man took over the rule of his father's territory. This explains Abraham's urgency to fetch a cousin bride for Isaac before he died. Isaac was not Abraham's firstborn son, but as the only son of his half-sister wife, Isaac was Abraham's proper heir. Before he died, Abraham gave grants to the sons of his concubines and sent them away from Isaac (Gen. 25:6). The sending away of non-ascendant sons drove the Hebrew dispersion throughout the Ancient Near East.

Some Hebrew wives were their husbands' cousins. That is the case with Keturah who bore Abraham six sons (Gen. 25). Recognizing this two-wife pattern is essential to understanding the social structure and marriage customs of the early Hebrew. (4000-2000 BC).

The ancient custom of having two wives pertained only to Hebrew men who ruled over territories. The two wives resided in separate settlements that provided security along the ruler's borders. Their border settlements were served by warriors, craftsmen, herdsmen, and physicians. 

Abraham's territory extended between Sarah's settlement at Hebron and Keturah's settlement at Beersheba. These are shown on the map above. Note that Abraham's territory in ancient Edom (Idumea in Greek) does not correspond to the modern Israel.

Keturah’s settlement at Beersheba was the site of seven wells. (Be'er means well.) These wells have been identified by archaeologists. In Abraham’s time, Sarah’s settlement at Hebron had four water sources. It is likely that these wells were also places of ritual cleaning. Shrines were built at wells, and these were tended by priests and their families. The wells provided water for the herds and flocks. Though the water shrines were under the control of regional lords, visitors were welcome to the water. Wells and water shrines were neutral ground and natural gathering places. 

Some Hebrew men met their future wives at wells. Among them were Abraham, Jacob, and Moses. Abraham's servant found Issac's cousin bride at her father's well in Padan-Aram. Jacob met his cousin wife Rebekah at her father's well (Gen. 29). Moses met his cousin wife Zipporah at her father's well in Midian.

The arrangement of the narrative of Sarah's death and burial before the account of Abraham's marriage to Keturah is an artful way to imply that Abraham took a second wife only after Sarah died. However, what is implied is not supported by the biblical data. 

Related reading: Hebrew Rulers with Two Wives; Keturah was Abraham's Second Wife; The Hebrew Hierarchy of Sons; Cousin Brides Among the Hebrew