Kurdish "Qarmatians" in the 13th-century

Ibn al-Jawzi, the medieval Muslim jurist and historian, reports the presence of Qarmatians among the Kurds. He likely drew this information from earlier authors who had similarly described parts of the Kurdish mountains as home to "Qarmatians." How should such reports be understood?

Medieval authors frequently employed broad and often imprecise labels when describing entire peoples or regions. For this reason, it is doubtful that substantial communities of Qarmatians, in the strict "developed" sense, existed throughout the Kurdish mountains during Ibn al-Jawzi's time. More likely, the term was being used as a catch-all designation for populations perceived as heterodox/non-Muslim.

What is particularly significant is that Ibn al-Jawzi's testimony suggests that large segments of the Kurdish population were still viewed as non-Muslim in the thirteenth century. The largest segment in my opinion for this period. This does not imply that Islamization/Arabization had not already made progress in Kurdish regions, nor does it mean that Muslims were absent from those areas. Rather, it indicates that, at the collective level, Kurdish communities continued to be regarded by contemporary observers as lying outside the bounds of Islam and that these observations were true since Kurds as a collective did lack bare minimum Islam. This conclusion by Muslim authors about the Kurdish regions and population would hold true for centuries to come.

Ibn al Jawzi writes: 

Their (Qarmatians) followers are of different types. Among them there are people whose understanding is feeble and whose sight is weak, who are over-come by stupidity and silliness and who know nothing of the sciences. And (among them may be ranked) the people of Iraq, the Kurds, a multitude of Persians and some stupid young people, the error of all of whom is of the same kind. 

And there had been people (among them) who threw the idols down and removed them. And among their followers there is a group the reign of whose ancestors had been cut off by the rise of the empire of Islam, like the Khusraws, the Dihqans and the children of the Magi... whose bosoms lodged the secret hatred which is like a secret illness. Behold the imaginations of the destroyers which kindle its flames (i. e. those of the secret illness). There are even some distinguished people among them, but a considerable number of their followers are heretics, philosophers and dualists who consider divine laws as common (mundane) laws (nawāmis mu'allifa) and the prophet's miracles as deceitful forgeries.