That is all very true, but these maps are far from meningless. The author maps political regions rather than nations in the modern sense. Take for instance the way Spain changes colour each time there is a major dinastic change. Although nationalism arose as major political force only with the birth of modern democracy (if you want to give power to the people, defining who the "people" is becomes much more important), it wasn't born out of thin air. For example, you can hardly get a more nationalistic text than the portuguese epic poem "Os Lusíadas", published in 1572 (perhaps significantly, in that one corner of Europe that has hardly budged since the 13th century.) The king is praised but the most praise goes to the intrinsic value of a "portuguese people". There are also many many instances in the history of Medieval Europe of townspeople rising to fight a power that is perceived as a foreign occupier. Most of these regions would have been easily recognized by the people of the time as important political entities. Except for the Holy Roman Empire of course: a merchant who'd have needed a degree in political science to figure out to whom was he paying toll when going from town to town.