It has been a few days, and I've been hard at work, so here's an update.
As I started doing research on preplacement for cities, I came face to face with some startling realities from history.
First, is that at 4000 BC, many of the groups that are widely dispersed later on, are very tightly packed still in the Mesopotamian area. In addition to the ancestors of the Jews still being imbedded in the Babylonian/Sumerian area, you also have the Greeks, Romans, Scandinavians, Russians, and perhaps others. The Carthaginians haven't yet moved away from Tyre/Mesopotamia. The pathetic Spanish aren't even going to start developing a distinct culture (at least one that isn't swept away by the Phoenicians or Romans) for another 4000 years!
As I did my research (an I have been doing a lot of it), I found that most of the groups that I would want to represent on my map have settled into a recognizable location by around 550-500 BC. (By recognizable, I mean that they are close to where they will later end up). The Rus/Slavs are still in Caucasus, but at least they aren't in Mesopotamia. The Scandinavians are somewhere between the Sea of Azov and the future location of Kiev, but it won't be long before they reach Scandinavia. The Goths have finally
left Scandinavia, to make room for our Vikings to move north (I would have hated to start the Germans in Denmark and the Vikings east of Prussia!). The movement of the Goths into Germany forced the Celts to move southwest into Gaul, so they at least are in a good spot (again, recognizeable). That would be my ideal starting point for the Celts, rather than Londinium, so that they would be on hand to oppose Roman expansion. Besides, I found a fairly well-documented
article that states the "Celts" in Britain would be better classified as Picts, and were of separate racial origin than the Celts in Iberia and Gaul. I'm going along with that, so if I do have anyone starting in Britain, they will be called Picts and they will start in Scotland.
The list goes on. Ethiopia didn't become established until 500 BC. The Jews would be in Jerusalem in 500 BC (having been recently freed from Babylonian captivity by Cyrus the Great) and would be ready to begin building their Second Temple Mount. In 500 BC the Maya are just beginning to emerge as a civilization. Rome has just emerged as a power distinct from the Etruscans and other peoples of the Italia penninsula. The Joruba civ is still pretty backward; they won't have an Iron Age for another 150 years, and are still called the Nok, but at least they are on the radar. We can also finally figure out where the ancestors of the Zulu are. This is also a convenient date to start, because if we start at 530 BC, Egypt will still be independent (the last independent pharoah is about to die). Persia sweeps through just before 500 BC, and they also take about half of the Greek cities in the eastern mediterranean. So it will be good to begin before Persia gets incredibly big and unbeatable.
What will this look like?
Well, I will have to still preplace some cities. It would be completely a-historical to have the Goths (as Germany), the Rus (as Russia), and the Celts (as Spain-France-England) get a settler and worker to begin at 500 BC, and then also give this same starting material to Egypt, Persia, China, etc. I moved the starting point to 500 BC so that we could have historically recognizeable starting locations for everybody, but I'm not going to ignore the 3500 years of history that has already passed at that date.
So Egypt is going to have Memphis, Thebes, Sais (the current capital of the 26th dynasty, located in the Nile Delta), Elephantine (the southern border), and Meroe (a Nubian city, the capital of the 25th dynasty of Egypt, and still a very egyptian city). There will be a Monument and Temple preplaced in most of these cities, and the Pyramids will be located already in Memphis (the closest city to Giza that will be represented). I can't age the Pyramids to give double culture already, and I won't give Egypt 500 culture to start with (that would be accurate but too unfair), so there will be some historical concessions made to playability.
That is an example of city preplacement using Egypt. Other civs with preplaced cities will include Greece, Carthage, Rome, Persia, India, China, Maya, (and maybe the Olmecs--they are in decline in 500 BC, so I may be able to leave them out, in favor of putting the Aztecs nearby).
Civs with preplaced cities are ones that are already established in 530 BC. Some of the cities will already have temples, etc. Elephantine, for example, will have a Marketplace. Rome will have a Barracks (they need it--they are practically suffocated by Carthage and Greece at this date). I will be preplacing completed wonders in all the appropriate cities, like the Hanging Gardens of Babylon, The Oracle, The Temple of Baal, etc. (Damn, I just remembered that I need to preplace Stonehenge or remove it from the game, and I don't have a civ there. It looks like it will be out, sorry.)
Civs that are in decline (like Egypt), or have already received the benefit of their Golden Age (like Persia), will have the "triggers Golden Age" flag removed from their UU. Persia is already about as big in 530 BC as it ever gets, so I would say that they shouldn't have a Golden Age triggered, even though historically they are IN their golden age in 530 BC. I don't want them to get too powerful, or else Greece and India won't be able to defend themselves against Persia. Greece, on the other hand, is indeed about 30 years away from triggering a golden age, so I'd say leave the golden age flag on the Hoplite.
To make the Advanced Civilizations (the ones with preplaced empires) truly advanced, I am giving them the entire first row of techs in the ancient era to start with. How? I am rolling them into two techs, probably called "Foundations of Civilization" and "Advances of Civilization". These techs will both occupy the first row of the tech tree, and will contain, collectively, the following techs: The Wheel, Warrior Code, Pottery, Masonry, Bronze Working, Writing, Mysticism. They will also enable building roads, irrigating, and seeing domesticated animals and foods on the map. The Advanced civs will start with these two techs. Although most of all of these civs are also already in their Iron Age, I won't lump Iron Working into the two techs.
These advanced civs will also have NO access to Settlers in the ancient era, so their only means of expansion will be through conquest. Still, with up to 7 cities at the start, many of them will already exceed the optimal city limit.
The civs that are not yet established in 530 BC (many of them are still moving around a lot) will be called Migratory Civilizations. These are peoples that have been moving a lot in the past 500 years before the start date, and are about to start settling down (within the next 300 years). Anyone not emerging within this time period on the historical timeline, just won't be included. So...there won't be an American civ. Or Spanish, English, French, etc. The Scandinavians, Celts, and Goths who were the forerunners of these civs will be in their places instead.
Migratory civs, probably in most cases, will not start with any techs at all (there might be an exception, but it wouldn't make sense since the two starting techs equal about 3-4 techs apiece). They will be able to build settlers (at half cost), and they will also be able to build Warriors at half cost. Because the migratory civs will already be in place to block one another from settling too far out of their historical territory, and because there will be no settlers generated by the advanced civs until Feudalism, I don't think there will be so much of a need to preplace Barbarians to block certain areas of the map, with the exception of Australia and the southwest Pacific. Anyway, that is my hope.
There might be a need to help Migratory Civs "catch up" technologically at some point, with something like the Statue of Liberty. The Goths and Celts, for example, should probably have a "Renaissance" small wonder that gives them the effect of a Great Library for a short period of time. This might be placed on the Printing Press tech and go obsolete with Naval Tactics or Enlightenment.
Like RoC and RoCX, the "difficulty" of the scenario will be controlled largely by which civ you choose to start with. Starting with Rome you might have a bit of a challenge. Starting with Ethiopia, you would have a big challenge. Persia would be easy in comparison (and I'll really have to work to make sure they are overpowered). The reality was that Persia in 500 BC had reached the manageable limits of an empire, so they spent the next 250 years trying to hold the empire together rather than expand it. If I can recreate that challenge through a forced starting government, corruption, and/or optimal number of cities, it will be great.
I'm working on the civs and map right now, and have them about halfway done. Hopefully this plan will be more sound than the last one.