The Ismailis (Sevener) use of the Satr doctrine

The Fatimids (ancestors of the Ismailis and Bohras) have been known to use satr (concealment from the public eyes) very often and very frequently (to explain the whereabouts of certain Imams or line of Imams). A few examples are

• In the first instance they used it to somehow explain the whereabouts of Ismail ibn Imam Jafar al-Sadiq(as)
• Then it was used to justify and explain the missing Imams (the Imams #8, #9, #10 and #11)
• Then satr was again used to explain the bohras (mustalian) belief in the 21st Imams and his descendents 
• Even other off-shots of Ismailis like the Druzes believe in a ghaybah like satr. The Druzes are awaiting the reappearance of the Fatimid Imam al-Hakim

The Ismailis and the Bohras have continuously maintain that while the Imams are in the period of satr, they (Imams) are continuing propagating the Ismaili doctrines through his representative (Dais). 

Personally, I don’t think we have evidences to support the Imams in Satr (Ismailis Imams #7, #8, #9, #10, #11). 

A follow-up from the Ismaili definition of Satr as a period where their Imams were hidden from the eyes of their followers.

• Who are these powerful enemies (of the Ismailis Imams) causing their Imams to go into satr? 
• Are there any historical evidences that can back this claim about these oppressive villains?
•  What are the names of Dais who propagate the Ismaili message on behalf of the Imams in the period of Satr?

Even the most premier Ismaili historian, Dr Farhad Daftary couldn't give a reasonable explanation on the period of “Satr”. He couldn't find anything worth mentioning about them in his book. This is what he wrote (a total of two paragraphs about the Ismaili Imam in Satr)

Chapter 3, Page 87 from the Book The Isma'ilis: Their History and Doctrines - 2nd Edition by Farhad Daftary

Early Ismaılism, or the pre-Fatimid period in Ismaılı history, is one of the most obscure major phases in the entire history of Ismaılism. It extends from the proto-Ismaılı origins of the movement, in the middle of the 2nd/8th century, to the establishment of the Fatimid caliphate in the year 297/909, a period of almost one and a half centuries. Little reliable information is available on the history and doctrines of the early Ismaılıs who contributed to the success and intellectual development of this branch of Shi'ism. As a result, many aspects of early Ismaılism continue to be shrouded in uncertainty, causing irreconcilable disagreements among modern scholars regarding some key issues and events.