Daylam and Gilan were the only regions to successfully resist the Muslim conquest of Persia, although many Daylamite soldiers abroad accepted Islam.
Both the Zaidis and the Nizaris maintained a strong presence in Iran up until the 16th century rise of the Safavids who espoused the Twelver sect of Shia Islam.
In the 930s, the Daylamite Buyid dynasty emerged and managed to gain control over much of modern-day Iran, which it held until the coming of the Seljuk Turks in the mid-11th century.
[3] According to the Byzantine historians Procopius and Agathias, they were a warlike people and skilled in close combat, being armed each with a sword, a shield, and spears or javelins.
According to the Letter of Tansar, during this period, Daylam, Gilan, and Ruyan belonged to the kingdom of Gushnasp, who was a Parthian vassal but later submitted to the first Sasanian emperor Ardashir I (r.
[2] The 6th-century Byzantine historian Procopius described the Daylamites as; The equipment of the Dailamites of the Sasanian army included swords, shield, battle-axe (tabar-zīn), slings, daggers, pikes, and two-pronged javelins (zhūpīn).
[8] During the reign of Harun al-Rashid (r. 785–809), several Shia Muslims fled to the largely pagan Daylamites, with a few Zoroastrians and Christians, to escape persecution.
[10] In the mid 9th century, the Abbasid Caliphate increased its need for mercenary soldiers in the Royal Guard and the army, thus they began recruiting Daylamites, who at the period were not as strong in numbers as the Turks, Khorasanis, the Farghanis, and the Egyptian tribesmen of the Maghariba.
From 912/3 to 916/7, a Daylamite soldier, Ali ibn Wahsudhan, was chief of police (ṣāḥib al-shurṭa) in Isfahan during the reign of al-Muqtadir (r. 908–929).
[10] Islamic sources record their characteristic painted shields and two-pronged short spears (in Persian: ژوپین zhūpīn; in Arabic: مزراق mizrāq) which could be used either for thrusting or for hurling as a javelin.
"[2] The Church of the East had spread among them due to the activities of John of Dailam, and bishoprics are reported in the remote area as late as the 790s, while it is possible that some remnants survived there until the 14th century.
[2] The name of the king Muta sounds uncommon, but when in the 9th and 10th centuries Daylamite chieftains appear in the spotlight in massive numbers, their names are undoubtedly pagan Iranian, not of the south-western "Persian" type, but of the north-western type: thus Gōrāngēj (not Kūrānkīj, as originally interpreted) corresponds to Persian gōr-angēz "chaser of wild asses", Shēr-zil to Shēr-dil "lion’s heart", etc.
In 963, the Buyid ruler of Iraq, Mu'izz al-Dawla, popularized Mourning of Muharram in Baghdad, which may have played a part in the evolution of the ta'zieh.