Idumeans also known as Red Jews and Hyrcanians are the descendants of Edomites forcibly converted to Judaism by John Hyrcanus around 100BC when he ordered the entire population to be enslaved and then freed. Their name Hyrcanians comes from John Hyrcanus. They are also known as Ercolians or Hyrcanian Jews.
Although Hyrcanians accept the Mishna they do not have a very sophisticated understanding of Judaism and are comparable to Samaritans, Falashahs and other kinds of Karaites such as the 5th century Ishmaelites described by Sozomenus.
According to Jewish tradition, Idumeans are associated with Christendom because they believe that Rebbe Yehoshuah Minzaret was not really a human but the incarnation of Abraham's Visitors as one person.
In the 7th century they worked hard to make Hagarim and Toshavim out of all the gentiles of the Middle East such as for example the Elagabalites.
The Idumeans and their Pahlavi Hagarim made a treaty with the house of Sassan in 632. The house of Sassan were allowed to place Yazdegard III on a throne controlled by Idumeans and their Pahlavi Hagarim.
However, Karaite Jews conquered the western Idumeans in 633 so the Sassanians and the Pahlavis defended themselves but were suppressed in 636 by Umar who got the Idumeans on his side by arranging a marriage between a princess from the House of Sassan and a prince from the Idumean house of Ali to rule after Yazdegard III which they eventually did when Yazdegard III died in 651. However, a civil war broke out in 565 which caused Muawiya to secede Damascus away from the Idumean confederation.
Muawiya eventually made a treaty with the Idumean confederation again in exchange for rule until his death in 680 but then his son Yazid killed the Alid Prince and broke away again which allowed ibn Al-Zubayr to take control of the Idumean confederation.
Overall, the archaeological record attests to these Idumean-style rulers in the area of the former Persian Empire from 651 to 692 a total of 21 years.
As they began to be conquered one by one by Abdul Malik, he adopted their style and the Idumeans only began to be forced to accept the Anno Hegira from 692AD after Abdul Malik realized that Israel-centric uprisings would keep on coming back again and again if he did not eliminate the need for Mosaist-hierarchs.
Thus the Idumean rulers vanished from history. They might have been involved in the establishment of the Khazar Empire after that but otherwise seem to melt into the general Jewish community after that.