The Great Rift

Story idea based on the "Guns, Germs and Steel" theory. Apply a few subtle tweaks to the plants and animals of the world and we get a completely different path for civilization.

The cradle of civilization moves from the Tigris/Euphrates valley to The Great Rift valley, centered around Lake Victoria. Ukerewe Island (the largest island) is the capital, with the main city state in the peninsula to the East, the Mara Region.

Prickly Pear fruit has been cultivated into a super-food. The sugars and proteins are much higher and fat is a bit higher, it has about 400C per 100g (instead of it's 41C). It already has a high vitamin-C level, but we'll bump that up just a bit. You cannot just drink the juice of a cactus, it's too acidic due to CO2 being stored as an acid (the cactus photosynthesis during the day and breaths at night), our version will go through a phase where the "leaves" die, turn purple and the needles fall off, at this point they basically become water bottles, slightly sweet.

Entada rheedii is edible when cooked with no ill side effects (like hallucinations), maybe play around with the effects of undercooking - could be something to kill fear, or induce mild hallucinations in warriors. It's a vine, so the farms will be more vineyard like. Real version, seeds weigh around 1oz/28g, in our world they'll weigh around 75g.

Foxtail grass may be interesting for it's flammability. Parthenium as a rubber.

Egyptian Mongoose are kept like cats; not quite domesticated, but friendly towards people, allowed to roam because they kill pests.

Vervet Monkey are kept like dogs. They help with basic tasks like herding and hunting. Traditionally, they would provided a perch wherever people were camped or homed and when not with people, they would keep watch (much like dogs) from there. They form tight companion bonds with their people. Much like dogs, a number of breeds have arisen ranging in size and temperament. Shepard-monkeys are on the smarter side with longer arms and legs for running. Hound-monkeys are stockier and more aggressive, originally breed for hunting, later adapted to war.

Ostrich are kept as the primary livestock, specifically a descendant of the Somali Ostrich. The fictional version is a bit shorter in both the neck and legs and a bit meatier.

Zebras, Black-Rhinos and Elephants will be used as beasts-of-burden, which Rhinos being particularly trained for war, though their origins are as plows having been trained to dig up fields.

Cichlids will have to play a part.

The people will be descended from the Luo and Iraqw. Look at Engaruka. The divergence from reality happens in the late Mesolithic era.