The site of "the Plain" has been variously conjectured.
Failing conclusive archaeological evidence, the Cities of the Plain must be listed as lost.
In the book "Ancient Secrets of the Bible" by Charles E. Sellier and Brian Russell page 37-39, and 91-92 they reported that the Ebla tablets were unearthed in northern Syria in 1976. They numbered about twenty thousand clay tablets from the city of Ebla at the height of power in 2,300 B.C., with a population of 260,000 people before it’s destruction around 2,250 B.C. They are known today as the Eblaite Geographic Atlas containing a list of 290 place names from the travels of a merchant before 2,300 B.C. One of the names in the list refers to the name ‘Sadam’ or the biblical Sodom presumed to be below the Dead Sea. They presented that these tablets identify the ruins of Bab edh-Dhra as Sodom but it did not state that the ruins of Numeria as Gomorrah (a short lived city).
The five cities of the plain (circle) of Jordan, were well-peopled around 2065 B.C. at which point they were abandoned, as found in archeological facts. They were in the Vale of Siddim (Gen. 14:3) possibly the southern end of the Dead Sea, now covered by water. The site of Bab ed-Dra’ (Babedh-Dhra) on the Dead Sea belongs to the age of Sodom and Gomorrah as its remains date from about the last third of the third millennium, when occupation here came to an abrupt close.
Until recently it was commonly felt that Abraham lived in the Middle Bronze Period (c. 2000-1500 B.C.), but an electrifying new discovery in northern Syria in 1974 at Tell Mardikh (Ebla) has caused Noel Freedman to place him (Abram) in the Early Bronze Period (2950-2000 B.C.) at a time when Ebla was at its height of power and influence. A royal library was found here consisting of 20,000 clay tablets, 80 percent of which were written in Sumerian and the rest in an unknown Semitic language akin to Hebrew that is now called Eblaite. Located halfway between modern Aleppo and Hama, at the top of the Fertile Crescent, the city was in the heart of Abraham’s ancestral home territory of Haran and flourished in c. 2200 B.C. Names like Jerusalem, Sodom, Gomorrah, Haran, and Ur appear in the texts.
Some scholars state that the above claim has been disproved.
If you have been grasping what this book is stating about Abram and Abraham, you can see the dilemma of recent scholars and archaeologists in that they are in conflict with dates. Abraham seems to be dated in the Early Bronze period and is also around in the Middle Bronze Period even though he was reported biblically to have only lived for 175 years, "...and died in a good old age, an old man, and full of years..."
As the Bible said Abram in Genesis 13:18 went to the forest of the giant trees of Mamre to live and build an altar to the Lord. This area is now a dry and barren landscape.