The Yazidis are Kurds (or Medes as they were), an Irani people. They retained their version of Zoroastrianism through the persecutions by Islam (Moslems consider them devil worshippers)
The Mandaens revere Adam, Abel, Seth, Enosh, Noah, Shem, Aram and especially John the Baptist as the founders of their religion and consider Moses, Jesus and Mohammed as false prophets -- these guys seem to be descendents of Abraham and may very well be some of the "lost tribes". They believe in strong dualism too, like the Zoroastrian belief (unlike the Yazidis who believe there is no "satan" and good and evil reside in each person). Of course the fact that they consider the founders of Judaism, Christianity and Islam as false hasn't really helped them be liked :)
Druze seem to be a syncretism of Abrahamic beliefs mixed with Platonic and the Allawis are Gnostics imho.
How does John the Baptist fit in for the Mandeans? Seems like he has nothing to do with Adam and Enosh and those other early Old Testament guys.
Fascinating, thank you.