@Defender, perhaps similarly to the demonic horde's slow arrival there could be some kind of background empires going on, you haven't discovered them so you only know of the few kingdoms near you but these big empires exist and grow far beyond, maybe you get word 'sir a strange green creature has arrived in our court, it seems friendly but we do not understand it' this turns out to be an orc explorer, a creature no one has seen before, we aren't sure what to do with it, to jail it and so forth.
Finally understanding it, it talks of an empire so large that our kingdom would be a mere speck compared to them, and turns out he's underselling it, Aslona and the realm of men have maybe 50'000 men at this point, this is your army, bandits and rebels, peasant groups and background population,
The Orcish empire across the sea has 110'000'231 people, imagine that, imagine declaring war on them and being attacked by an army that has more members than your entire race, and that's just a scouting party, you'd have to surrender quickly and become a vassal state of the orcs, and hope they were friendly
PS, Give that 445 code a try though, it's kind of like the above scenario, I played a game once where all nations had around a million or so units, some slightly less some much more, it was insanity, I basically hid away making sure no one attacked me, picked away at exploration and any minor groups and tried to grow my strength in the background, finally one of the nations got beaten back so badly by an army of millions of units that I was able to vassalise them, and togeather we grew to the point that I could compete with these kingdoms, bearing in mind around 5 million units had died in the fighting meaning all kingdoms and empires were much weaker by the time I could actually join the real game, turned into a few nasty wars and ended with a three way alliance of me, my vassals and some kappa people