Boris Gudenuf
Deity
Oh, I agree. The clear majority of the evidence points to the Steppe Hypothesis, but the Anatolian Hypothesis still has enough scholarly supporters not to be in crackpot territory.
Agreed. And whether or not Anatolia was the PIE 'homeland' it definitely was the origin for the first 'agricultural migration' of farmers into Europe (they've analyized the DNA of the humans and their sheep and cattle, so this is as certain as anything in archeology!) and so was the 'homeland' for agricultural technologies in southwestern Europe, the Balkans, and Greece.
Given they're attested in writing a few hundred years later, I think we can safely assume someone was speaking something that was recognizably Egyptian and Sumerian. The Egyptian-speakers would even be in Egypt. Since the Sumerians were recent arrivals who displaced the native Ubaid culture (who did not speak Sumerian based on non-Sumerian toponyms), there's no telling where they were in 4000 BC, however.
My data may be out of date the way things are changing in archeology, but the earliest dates I have for either Egyptian hieroglyphs or Sumerian proto-cuneiform is about 3300 BCE, which puts them about as far from our 'start date' of 4000 BCE as modern English is from Chaucer. The connection between the two might be apparent, but translation might also be required.
Interestingly, the Egyptian speakers might have also just arrived. There were several cultures that have been identified in what is now the Sahara, which before 4000 - 3900 BCE was savannah, with lakes and rivers supporting herding and fishing. The African Humid Period (AHP) from about 12,500 to 3900 BCE made that possible, but then dried up into the wasteland it is today, killing off the cultures, several of whom appear to have migrated east, into the Nile Valley. Now, there were also earlier groups already in Egypt, like the Fayum A, Merimde and Badarian, all of which had been in Egypt for 500 - 1000 years or more and already had irrigation and agriculture, so which added what into what became Egyptian later is a very open question.
Point is that everybody was moving around both before and after the 4000 BCE Game Start date, which makes all the 'historical' Civs starting on that date in their later form pretty much a Fantasy.