And this was despite China annexing Tibet nearly 40 in-game years ago. You can see similar skewed populations on the Indochina-Siam border (six digit populations on the Indochina side, four digit populations on the Siam side), or the Chinese-India border (zero on the Chinese side, thousands on India's side). I suspect it's everywhere, but it's just more obvious in Asia because of the high population counts making differences in growth more visually obvious.
So could we get some improvements to population distributions? Maybe things like
- Industrial facilities causing small population spread like cities but weaker: This can simulate work camps and boom towns that pop up near major resource deposits.
- Zero-population hexes become population if a neighbouring hex has a high enough population: As population density increases, people will consider using land previously though prohibitively expensive to develop
- Population spread across borders: With a few very rare exceptions like North Korea, cross-border migration, shopping, and trade is fairly common for those living near borders. So population should spread across borders -- even if just at a greatly reduced rate.