Medan in Easton's Bible Dictionary
contention, the third son of Abraham by Keturah (Gen. 25:2).
Medan in Fausset's Bible Dictionary
("strife".) Genesis 25:2. Son of Abraham and Keturah.
Identified with Midian in Genesis 37:28; Genesis 37:36. The
Keturahites early merged into the Ishmaelite tribes.
Medan in Hitchcock's Bible Names
Medan in Naves Topical Bible
-Son of Abraham and Keturah
Ge 25:2; 1Ch 1:32
Medan in Smiths Bible Dictionary
(contention), a son of Abraham and Keturah. Ge 23:5; 1Ch 1:42
Medan in the Bible Encyclopedia - ISBE
me'-dan (medhan, "strife"): One of the sons of Abraham by
Keturah (Gen 25:2; 1 Ch 1:32). The tribe and its place remain
unidentified, and the conjecture that the name may be
connected with the Midianites is unlikely from the fact that
in the list of the sons of Abraham and Keturah Midian is
mentioned alongside of Medan.
Medan in Wikipedia
According to the Bible, Medan (Hebrew: מְדָ֥ן "contention; to
twist, conflict"); also spelt Madan was the third son of
Abraham, the patriarch of the Israelites, and Keturah whom he
wed after the death of Sarah.  Medan had five brothers,
Zimran, Jokshan, Midian, Ishbak, and Shuah.
Apparent and approximate emigration patters of Abrahamís
children to Katurah, excepting those of whom insufficient is
known to draw a conclusion.
Josephus tells us that "Abraham contrived to settle them in
colonies; and they took possession of Troglodytis and the
country of Arabia the Happy, as far as it reaches to the Red
Sea." Abraham, in all probability, tried to keep them apart
from Isaac to avoid conflict while fulfilling God's commission
to spread out and inhabit the globe. Little else is
know about him. 
There is no known connection to the Madan people of Iran and
Medan Scripture - 1 Chronicles 1:32
Now the sons of Keturah, Abraham's concubine: she bare
Zimran, and Jokshan, and Medan, and Midian, and Ishbak, and
Shuah. And the sons of Jokshan; Sheba, and Dedan.
Medan Scripture - Genesis 25:2
And she bare him Zimran, and Jokshan, and Medan, and Midian,
and Ishbak, and Shuah.