Tahash was one of the eight sons of Nahor, Abraham's brother, by his concubine Reumah. He is mentioned in the genealogy in Genesis 22 as part of Abraham's extended family. Tahash is a lesser-known biblical figure, but his lineage is important for understanding the family relationships surrounding the patriarchs.
After the binding of Isaac, Abraham learned about his brother Nahor's children, including Tahash. This news connected Abraham to his extended family in Mesopotamia.
Tahash was born to Reumah, who was Nahor's concubine, a common practice during the time of the patriarchs. This placed Tahash in a secondary lineage compared to Nahor's sons with his primary wife Milcah.
Through his father Nahor, Tahash was related to Bethuel, who was the son of Nahor and Milcah, and thus also related to Rebekah, who later became Isaac's wife.