As for JFD's Alternate Leaders mod, I don't know, I don't really see the purpose of the mod as trying to reduce mod civs into as many vanilla civs as possible. I know people's definition of what a civilization is differs radically, but the trend on Civfanatics seems to be to want to group every civ into broad cultures (which is odd because the forum is usually against the giant blob cultures that Firaxis tends to do in the base game).
Generally, I tend to view two things as the same civ if it's ethnically and culturally the same people and it's a clear case of a sole successor state. If there's a a dramatic shift in the ethnicity or culture or there's multiple prominent successor states that continue to co-exist, I'm more inclined to treat them separately. I'm also not really a fan of grouping a predecessor civ with a later civ.
So, I think I'm just going to go with my original plan to only do Xia with China (even though it's a predecessor state, my Xia mod is clearly designed as “China”
.
For Kievan Rus’ – Russia, first, I’m not grouping them because I don’t want a bunch of angry Ukrainians complaining on the workshop page that the mod is too Russian again
I see nothing wrong with discussing Kievan Rus’ as part of Russian history and nothing wrong with discussing it as part of Ukrainian history. However, for something like this, it’s the issue of grouping a predecessor state that has several distinct successor states today. Actually, I wouldn’t really group Kievan Rus’ with either Russia or Ukraine. I sort of see the Golden Horde as a strict dividing line in the region, and Russia proper and Ukraine proper not really starting until the states that began to emerge following the conquest of the region. Now, if someone made a Rus’/Varangian/Rurik type civ, I’d consider grouping Kievan Rus’ in that.
For the Timurids – Persia/Mongolia, it’s the case of the Timurids adopting too much of Persian culture to still be considered just Mongolia but also not being Iranian (with Safavid – Iranian identity also being re-asserted in the area later) to just be Persia. There’s also the fact that the Timurids continued to exist in the Indian subcontinent even after Iranian identity was re-asserted in Persia. As I said in the More Civs thread, I’d be open to grouping the Timurids and Mughals together (since they’re both technically the same Gurkani Empire).
For Mali – Songhai, I don’t really see much reason to group them besides geography. Its two different ethnic groups (Mandinka vs. Songhai) with two completely separate centers of political power. Mandinka successor states also continued to exist after Songhai conquered the area. There are more closely related civs in Europe that similarly conquered/integrated each other’s territory that the forums would argue like crazy to be kept separate.
For Harappa – India, later Indian ethnicity and culture is so derived from the Aryan migration into the subcontinent that I don’t really think it works to group it with a culture that predates it.
So, that's my reasoning. The thing also is, it's really easy to just edit one file of a mod to group a civ. I feel if anyone cares that much about grouping a certain civ, they can just do it themselves, so I'm not too concerned about doing it myself.