Europe too, historically. It's like the Nile Valley but a whole damn continent. You can't go 20 miles without being within 5 miles of the most utopic, lush, fertile land the world has ever seen. It's no wonder Neolithic Europeans did what they did; rather, I half expect more of them. You give the Afitic race (East African intermediaries) just the one stretch of land comparable to what 90% of Europe is in the Dongola Reach and you get Kerma within 3000 years. Why did it take them so long to build something like Cucuteni-Trypillia? There should've been hundreds of these city-states all vying for power over Central Europe thousands of years before the Bronze Age.
America served as a good example since all the variation is baked into one single country today, though the sentiment carries across Europe.
I suspect the reason the late European Neolithic farmers did not create many civilizations early was because of culture, traditions, and ideology. The reason the Native Americans from the US did not create an Inca-level civilization was that they simply did not live like that.
Culture, ideology, and beliefs are the reasons why the northern Native Americans did not develop large civilizations like those in other Mesoamerican regions in Central and Southern America. Had they unified the land, it would have no doubt eclipsed the Incas, and it's hard to say if Europeans could have dominated them.
It was Cushitic ideology, culture, and tradition that set up civilization in northeast Africa altogether. Its roots go way deeper than Kerma, my friend. Kerma was the final stage of a complex civilizational culmination that stretched from the northern deserts on both right and left, and the Nile at the center. One can go deeper, but for the sake of the backdrop, it started 6400 years ago, in essence. That is when we see the rituals, megaliths, and complex organization in a specific manner that served as an institutional template for later developmental roots through a broad-spectrum geographic orientation and a continuous chain. And basically, it was a Saharan ceremonial economy that expanded towards different ecosystems.
So Kerma was not a lucky corridor at all; it was merely a late crystallization nexus of the aforementioned Saharan tradition, entirely retained, added with a stronger agrarian supplementary establishment. The "agro" in agro-pastoralism had a stronger presence (but it always had a presence), while the culture was pastoral with strong livestock expanse, added with a complex economic sourcing through a reinforced by a stronger agrarian supplement, and part urban sedentary nexus, an overall, mixed resource mobilization multiplex and diverse trade resource flow that had a strong spatial core (a core always existed). This was never a sedentary farming-based civilization. Everything existed before; with Kerma, the Cushites were able to expand to whole new scales.
It was not limited to this; Wawat, before the Egyptian sabotage, had wealth and capacity that would parallel Kerma with a different economic emphasis on higher trade, higher natural raw resource extraction, and lesser extent, agrarian sub-economy. Lower Nubia and Upper Nubia were seen as a single supra-regional sphere with sub-regional autonomy. Even before Kushite expansion, and Egyptian meddling in Wawat (they had too strong an economic and organizational rise for Egypt's liking), Kerma consolidated a senior role of the two, delegating Wawat to an autonomous region of a Kerma orbit as in power. Culturally and regionally, Wawat would retain a cultural prestige and economic presence even beyond this, deriving entirely from the same institutional ceremonial, ritual, and organizational grammar and having continuous intertwined relations until the pedigree divergence, while still maintaining contact in all avenues, still lowering distinction.
See, we Cushites had the institutional kit mixed in with the right economic-ecological dynamics. The Europeans during the same time did not have it. They did not develop mobilizable command institutions, legitimating rituals of power, a control radius, and the farming tech was not good enough. Also, they had fewer durable regimes for diachronic, expansionary conflict-capable dominance projection, given that we see the entirety of Europe being dismayed by the Steppe people in one fell swoop, showing in Britain and Iberia, where there was rapid ancestry turnover, with near-total male-line replacement, showing they were eliminated. Martial culture was definitely less than ideal.