If tribe was (I hope you'll agree) too small, and nations "too big", what in your view is the optimal scale for governance? Personally, the most logical conclu

If tribe was (I hope you'll agree) too small, and nations "too big", what in your view is the optimal scale for governance? Personally, the most logical conclusion for me is that national governance being the highest level is a local maxima, and I think I'd take a long bet that if humans are around in another 1000 years, there would be a necessary requirement for at least some form of planet-scale government.