a) Turks do that effectively ingame via the core change mechanic.
b) But wouldnt one city civs just become easy snack for larger civs? Wouldnt their tech trading just make overall tech speed faster, while failing to do any significant moves?
Portugal and Netherland are both big colonizers that contibute to the change of politocal landscape in the game. I cant say the same for, say, Switzerland.
a) there was the Horde / Mobile unit spawn point mechanic in the Genghis Khan scenario. Allowing nomadic civs to have mobile cities would be a starting point. They can only have city buildings that would be transportable. Like barracks, stables, smoketents, temple tents. I didn't think this through, so this idea is wildly unbalanced and doesn't consider stability, culture/control areas, or a dozen other things.
b) Tibet is another 1-city civ to consider. And actually, also Sumer, Akkad, Babylon, Assur or the Hittites. They were never stable empires for more than two centuries, but 1-city civs that managed to subjugate other cities for a short while. If we are at it, we could also customize independents as proper 1-city baits, like Chinese independents (600 scenario: start as one of the 1-city warring States, and unite China.) or, whatever, South American civs (Argentina, Peru, Paraguay, Colombia: possible to spawn earlier if the Spanish colonies break apart earlier than the regular spawn date.) Or, if HRE falls apart early, establish historical independence states. Same with Indian civs.
Naturally, the latter requires to have untangled civ/team slots. So it's not scheduled until the release after the next release. If ever.
On another note:
Even when empires collapse, they should (in my opinion) in most cases, just be nerfed instead of wiped off the map: collapse to core, lose all culture in core and be unable to use wonders, lose troops/experience, lose above-average technologies, lose diplomatic credetentials and trade agreements, make them into "minor" civilizations that nobody really cares about - in short, make them sitting ducks for would-be conquerors... But if no conqueror comes around, they would bounce back without the respawn mechanic.
I'm sick and tired of Scandinavia repeatedly collapsing and respawning (declaring their independence from the independents) when clearly nobody is interested in taking their cities. Arabia, Morokko, Tamils, Ethiopia, Russia: Let them collapse to core, brand them as minor civs for a certain time so that they're at a severe disadvantage.
