How should you estimate the size of your world population ?
In the times I have been trying to write the world I made I tend to wonder, when you build a faction, Nation, institution or Kingdom and something resembling itself as an organization do you ever think of how much is this specific group has in their amout and population ?
For example, when I writing some of the lore in my world, it is playing in the realm of nation building and so there is question at the back of my mind "How big and how populous I should make this nation ?"
Should I follow the realistic path of the world and it should range itself in the millions, but if the time period I set this is following pre-modern era how much is it exactly ?
Or let say modeling it in that modern era or futuristic era, what number can we consider it to be appropriate, is it so many that it can lead to burden within your world or you make it in the amount where it wouldn't leave a crisis in your world ?
What are your thoughts on this, if you do have something to comment I would love to see it.