There was an interesting article from the Atlantic that was posted quite a bit back on this thread that argued that IS was actually trying very hard to adhere to medieval traditions, which is something that makes their actions ever harder for us to understand [even if their reasons for doing so are very modern].
Edit found the link from earlier in this thread:
http://www.theatlantic.com/features/archive/2015/02/what-isis-really-wants/384980/
The issue is that to modern historians or social scientists, the concept of medievalness in other nations doesn't really make a lot of sense; there are plenty of things that have been done waaay back in Western tradition that is brought up again and again and again and again in "modern" Western culture. The concept of historical linearity breaks down completely if you examine how societies develop. Some examples:
We still love ancient Greek philosophy and refer to it abundantly in modern academia,
We love Kantian and Cartesian epistemology,
We use medieval flags, here Denmark is a prime example,
Plenty of Western nations still have kings, queens and knights while several "medieval" nations don't,
We still read and adhere to the Bible (with interpretations both "modern" (implicitly correct) and "outdated" (implicitly incorrect) depending on who you ask)
Stuff like flat earth adherents is usually associated with an attitude that's stuck in the medieval times, but the Christian anti-scientific backlash is a quite newer one, people used to get that the Earth was probably round,
Again, think of "medieval" Christian philosophy that was earlier strictly tied to Aristotlean physics (and therefore wrong), but we still use his poetics, for example, practically everywhere in the studies of arts, and refer to him all the time in philosophy for legitimacy,
We still swear by the Bible in court,
Some people swear to One Nation Under God,
We still use the dead Latin in biological sciences,
and lastly, outdated anthropology used to believe that examining "primitive" tribes was examining a proto-form of human development; that we could realize what we used to look like that way, act that way; this attitude is connected to the outdated idea of societies naturally progressing linearly forward towards the Western example, and it's just not true. Plenty of people have theorized that the traditions seen in tribal nations might actually not be several thousand years old, but rather just a few generations old (as with several traditions we ourselves imagine is a huge part of our history) while others have theorized that tribal nations might actually have once been living in city states, but have developed away from that. Both of these theorized probably have some truth to them if you go through local examples.
Still, it's mundanely normal for a "modern" Western person to appeal to naturality or have tribal nations in their imaginary of primitivity, stuck in undeveloped limbo for thousands of years.
"But Angst," others plea, "Some of these things aren't really old as they use modern components somehow/are infact modern/are part of a cultural necessity that naturally leads to our modern nation," and to that I say "So do these supposed "medieval" nations/no they're not, what does modern even mean if some attribute can both be ancient and modern in Western civilization but not in Arab/that's just wrong, several nations do well with those "necessities", others do worse because they have these "necessities"."
The conception of a proper linear development into industrial nations into service economies doesn't hold up either, as the development has so many facets that are both social, ideological and technological; each Western industrial nation developed very differently and the industrializing nations in the rest of the world are using a completely different road than we used to use.
Stop saying "medieval" about stuff you don't like except if it is, you know,
actually medieval, which means "In Europe In The Time Period Between Western Rome's Fall And The Renaissance". As we're not in that time period anymore, the term "medieval" is just used as a sticker you put to stuff that you think should've developed another way. But articulating your issue about it rather than calling it medieval is much more productive.
(I read the article a long time ago btw)