Mandaeism

Today I learned about a religion which has been existed in southern Iraq and Iran for a long time.
"Mandaeism is a monotheistic religion with a strongly dualistic worldview which has historically been practiced primarily around the lower Karun, Euphrates and Tigris and the rivers that surround part of southern Iraq and Khuzestan Province in Iran.

Mandeans seem to be indigenous to Mesopotamia and are certainly of Pre Arab and Pre Islamic origin.
In the Shahnameh (Persian for "Book of Kings"), written by Ferdowsi Toosi referred to a man named Mardas, an Amir lived about 800 years ago in the southwest of Iran (dasht-e savaran-e neizeh gozar) who seems to be one of the mandaecs, because he prayed to god after washing himself all the time especially at dawn. This religion also is called Moghtaseleh means "those who wash themselves a lot" (Ghosl in Arabic means Bathing) The term comes from Classical Mandaic Mandaiia and appears in Neo-Mandaic as Mandeyānā.".
Watch this clip.