The Torah does not provide a lot of background for Abraham and Sarah. Before following the couple when they “go forth,” however, it can be instructive to consider what is available in the text and midrash regarding their extended family and their ancestors. Here’s a family tree with links to Wiki entries for many family members. Some are extensive and well-sourced; a few, including the page for Terah, are not.
It can be just plain handy, in avoiding confusion, to note that “Nahor” is the name of both Abraham’s grandfather and his brother, for example, and that Iscah is often identified with Sarah (see e.g., this article in the Jewish Women’s Archive). It is interesting to notice how many of the ancestors in the Shem-to-Abraham line are named for divisions: e.g., Peleg [division], Serug [branch], Eber [opposite, or crossing over]. It is also helpful to note “others,” such as Nimrod, a large figure in midrash if not in the actual text, who also play a part in the story. (Nechama Leibowitz has a chapter on Nimrod and Babel in her New Studies in Bereshit/Genesis.*)
Finally, it’s particularly helpful, I think, to look at the overall progression of ancestors leading to the generation of Abraham and Sarah. Umberto Cassuto* discusses this lineage, reminding readers that the material “does not come to teach us ethnology, just as the first section of Genesis does not purport to instruct us in geology or palaeontology or any other sciences.” (p. 174, from Noah to Abraham):
When [chapter ten of Genesis/Breishit] seeks to explain how the whole earth became peopled through the three sons of Noah, it has a threefold aim: (a) to show that Divine Providence is reflected in the distribution of the nations over the face of the earth not less than in other acts of the world’s creation and administration; (b) to determine relationship between the people of Israel and other peoples; (c) to teach the unity of post-diluvian humanity, which, like antediluvian mankind, was wholly descended from one pair of human beings. — p. 175
Cassuto’s literary analysis focuses on numerical symmetry — based on months of life, as well as years — and other devices used to portray harmony and overall purpose in the text; the family of Terah, like that of Shem, is highlighted with detail beyond the first-born son. (Leibowitz — whose books are sometimes easier to find than Cassuto’s — often quotes him, along with other scholars, and her chapters on the portions of Noach and Lekh Lekha are no exceptions.)
For more on the backgrounds of Abraham and Sarah, here’s another good source for following this path.
*For complete citations and more details, please see Source Materials.
Click on the “WeeklyTorah” tag for more resources on the weekly portion throughout the year, or on a portion name for parashah-specific notes. (The series began with Numbers; posts for Genesis, Exodus and Leviticus are being drafted, week-by-week.) You can also zero-in on particular types of “Opening the Book” posts by clicking Language and Translation, Something to Notice, a Path to Follow, or Great Source in the tag cloud.
The “Opening the Book” series is presented in cooperation with the independent, cross-community Jewish Study Center and with Kol Isha, an open group pursuing spirituality from a woman’s perspective at Temple Micah (Reform). “A Song Every Day” is an independent blog, however, and all views, mistakes, etc. are the author’s.