Okay I just watched this, and John Green claims that the Crusades didn't really open up lines of contacts between the Muslim and Christian worlds because those lines of contacts were already open. How true is this?
I frankly can't believe someone would say the Crusades didn't open lines of contact between the Muslim and Christian worlds, but maybe I'm operating on a different definition of "open". The video has some problems for sure, but that's gonna happen when you cover well over a century of history in under 12 minutes with some of that time set aside to a bizarre tangent on animal crackers. That said, there's not any major issues regarding his treatment of Christian/Muslim overlap except what I consider the fairly dismissive conclusion he reaches, and which you're asking about.
Re: how true is it that lines of contact were already open between the Christian and Muslim worlds? It's pretty true. Shortly before the Crusades launched, the Seljuq Turks (the secular* dynasty ruling in Iraq, Palestine, Syria) had recently made some conquests of fairly large chunks of Byzantine territory in Anatolia. That means that yes, the Byzantine Empire (the centre of Eastern Orthodox Christianity) and the Seljuqs (effectively the face of the Muslim world at the time) had lines of contact, to say the least. As noted in the video, Christians had lived among Muslims for a long time, but the big annexation that happened under Arp Arslan before the Crusades meant a big influx of Christians under Seljuq authority, as is also referred to. It wasn't one-sided either - Muslims went to Byzantium and Europe, not exactly en masse, but they went.
That wasn't the only avenue by which the Muslim and Christian worlds were connected. The Italian city states, especially the ones with the strongest mercantile bents like Venice and Florence, conducted a lot of trade with Alexandria, which was the commercial centre of the Fatimid empire (the head of Shi'a Islam and long-standing political and theological opponents of the Abbasids and, by extension, the Seljuqs). They were very important trading partners to one another. So again - contact between the Christian and Muslim worlds.
However! I really don't think its fair to say that the Crusades didn't open up lines of contact. As he briefly touched on, the First Crusade established four Latin States, colonized and ruled by European Christians - Catholics, not Orthodox Armenians, whose attention to the region and lines of contact with Islam were naturally significantly more invested than the Venetians (at least, until the Fourth Crusade) or Florentines. They were a conquering political and military power whose stated purpose there was, by that point, to hold and defend Christian holy lands from Muslim rulership. I consider that a pretty major line of contact being opened. Islam had never had a connection like that to Europe - and I mean Western Europe and the countries we typically think of, Germany, Russia, England, and especially France - before then and wouldn't again until the modern era.
Did Christianity and Islam have open lines of contact before the Crusades? Definitely. No question, that's the case. But to say that the Crusades didn't open any lines of contacts? I just can't reconcile that. We're talking about an occupation that lasted close to 150 years with a huge amount of political, economic, military, and religious exchange.
I think you need to read the writings of men who lived and died with the Latin States as a part of their lives like Ibn al-Athir or Usama ibn Munqidh to get a better sense of the degree to which the exchange could have taken place. The Crusaders and regular interaction with Europeans was run-of-the-mill for these guys, just a part of their lives, which is unlike any experience prior. Which Arab chronicler recounts this anecdote escapes me (I can't seem to put my finger on it in any of my books), but one of the contemporary scholars shares a story in which a knight in the Latin States invites a Muslim noble to send his son to foster with the knight's family in Europe. The Muslim noble politely declines, but the idea of a young Muslim noble fostering in Europe is unimaginable outside the context of the Latin States.
In this regard, I see it as though the door to the Muslim world was cracked open, there was exchange happening, but the Crusades really pushed it open. It was fairly one-sided, lots of Europeans went to the Holy Land and very few Muslims went to Europe, certainly not in force, but the relations between the Muslim and Christian worlds were enormously impacted by the Crusades. This is why I see it as surprising that he would say the Crusades didn't open any lines of contact. Yes, they existed before, but the Crusades tremendously expanded them.
*Note that when I say secular I mean that they ruled by virtue of their political and military power by right of conquest as opposed to by religious authority, not that they weren't religious. They were unquestionably Muslim and closely tied to the Abbasid Caliphate, who were the religious authority in the Seljuq empire.
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