It is apparent that we don't agree on what defines a group of humans to be a sort of 'nation-state'
At which exact point in history would you point to as the defining moment where 'nation-states' begin?
Do you judge all historical concepts purely by how they are in the current day?
Concepts develop over time, those societies are absolutely part of the beginning of current day nation-states no matter how diverse in culture they may have been (which is something we still see today)
In political science, the nation state is commonly understood as a (relatively) recent development and not a feature of medieval Europe. 15th century Spain is sometimes given as one of the first big steps toward the modern nation state, though it would take some time (centuries) for the phenomenon to spread and to develop into something like its modern form. Like anything there's not 100% agreement over where the boundaries are et c., but in common usage and ordinary context, that's what's typically meant. If you're using it some other way you'll be misunderstood unless you define your terms.
> It is apparent that we don't agree on what defines a group of humans to be a sort of 'nation-state'
It's a pretty well-defined term. Obviously you're free to use your own definitions, but I assumed the article was using it in its standard sense, and I did likewise.
At which exact point in history would you point to as the defining moment where 'nation-states' begin?
Do you judge all historical concepts purely by how they are in the current day?
Concepts develop over time, those societies are absolutely part of the beginning of current day nation-states no matter how diverse in culture they may have been (which is something we still see today)