There have always, and I mean ever since people began to settle down in the Neolithic, polities with a strong tendency to conquer, subjugate and centralize larges tracts of territories, cities, rural areas and people. That is, centralization of power over resources.

We call them "empires" when we talk about the Ancient historical period, although in the Middle Ages there were empires too, archetypically, France. But medieval feudal kingdoms and other sovereign entities were pretty much the exact same thing, just smaller and perhaps sometimes nominally subject to an Empire. The Hanseatic League, the German and Italian mosaic of cities and principalities and other similar entities had to coexist and survive against these aggregating, centralizing polities all along their existence, until they finally were annexed too. 

And we're just talking about Europe. If you look at the Indian world, in the subcontinent and in SE Asia, or the Chinese sphere of influence in NE Asia, it was as centralized or more.

The conventional definition of "nation-state" is extremely weak and I have never bought it. Most often, it's something along the lines of "and unlike in the medieval era, now the people identified with the 'country' instead of their village", which is simply false as a universal claim.

The myth that "nations" appear only by magic when a bunch of monarchs put their signature on the treaties that concluded the Peace of Westphalia in the 17th century, and that those "nations" are identical to the States that happen to exist as a consequence, has no substance to it. And saying that it was an even later development, from the 19th century or even the aftermath of WW1 with the Wilsonian "principle of self-determination", even less.

More than 2000 years ago we already had Romans, and civil wars were fought over the right to receive full Roman citizenship by all its inhabitants. The English before Hastings were already fully aware of their national struggle to unify the territory, in opposition to both the different Celtic nations and the Norse. The Dutch, Portuguese and Catalan revolts against the Castilian-led Spanish Habsburg Empire were transparently national in nature.

The "modern nation-state" myth is simply a justification that the most recent existing states, extremely centralized due to modern technology and development, have constructed for themselves and the status quo they want to uphold. That's all. There is no objective difference with the "previous" order.