Civilization – ny way to see a digest of what resources civilizations / city states own

The money gained from performing a diplomatic mission is 350 + (50 * <era number>) where era number is just a serial number starting with 0 for the ancient era. In addition game pacing also affect this number: quick games modify this value by 0.67, epic by 1.5 and marathon by 3; or in other words:

             Gold in   Gold in   Gold in  Gold in
Era          Quick     Standard  Epic     Marathon
--------------------------------------------------
Ancient      234.5     350       525      1050
Classical    268       400       600      1200
Medieval     301.5     450       675      1350
Renaissance  335       500       750      1500
Industrial   368.5     550       825      1650
Modern       402       600       900      1800
Future       435.5     650       975      1950

I know of nothing else which can affect the gold amount.

Now, if I have a strong economy in the late game I typically gain another 100-200 gold per turn when in a golden age. That means that the only way in which a golden age is preferable to a diplomatic mission is when it lasts at least 3 to 6 turns. But usually by the time I get to the late game my golden age duration from great people is really low, and if you take into consideration that the influence gained is worth a few hundreds in itself, you'll see that a golden age looks less and less profitable in comparison. All this is especially true if you play in longer game speeds, which translate to higher gold.

Of course, golden age also nets production, so it's still a dilemma; but I do believe merchants are worth it from the financial aspect.

I am waiting for someone else to provide a better more accurate answer.

My observations are that City States can discover a resource before you do. An example of this is a city state I am allied with, will provide me with coal. However, I have not discovered coal and it does not even appear as a counter at the top of the screen yet. This proves that a city states technology is not in line with your own. A guess is they they would have access to all technologies cumulative of all player discoveries. This is because I find my greatest AI threat will upgrade to Infantry and then suddenly the city states around me upgrade to infantry.

Wildly guessing now! Another theory is that any CS that ally with a player gets their technology. If this is true, then it could mean that CS that are neglected as allies could have poor defence force technology. I will keep an eye on this on future games.

Secondly, if the city state does not have a worker they will be very slow to improve the tile. This is usually after they have survived a barb attack or foreign attack but have lost their only worker in the process.

I am unsure with the timeline of patches if city states do end up replacing workers because previously this was a problem. Not helped by a block that prevents gifting of workers. So no, you cannot help a CS with their tile improvements by using your own workers or by gifting workers.

As for the oil rig. It could be that they have discovered oil, but not oil rig tech. I am unsure about the build rate of worker boats. I do notice that the CS often works the sea resources quickly. But it could be a worker boat bug. i find that my automated worker boats will often move to a sea resource and then just sit on top of it. annoying. If the city state does the same, it could be connected to the same issue.