Nationalism in the Middle Ages?

nationalism is, unfortunately, once again on the rise in the modern day and while you might think that it has very little to do with the Middle Ages, you'd be wrong. because while the nationalism we see today didn't exist in the same form back then, the roots of it began to take hold even back then in the form of religious discrimination and of othering people who look or act differently. further, the nationalism that we experience today popped up in the 19th century and its loudest proponents popularized it by pointing to a very skewed, totally ahistorical version of Medieval history in order to reinforce modern ideas of racism and racial purity. so let's talk about it and see what we can do to combat it.