Sinia Island
Rifts Systems are in three parts, 2 active - 1 dead. The East Africa Rift System consists of Red Sea, Great Rift Valley, and Jordon Valley Rift. OTL the Jordan Rift is the inactive one.
However this doesn't mean Dead, there are still periodic small quakes [2~3], With occasion larger ones [6~7]. And the Arms change activity.
The Jordan Rift goes from the Gulf Aqaba, north to the Med, just south of Beirut.
So lets assume a increase in Jordon Rift about 80~90,000 years BP. as the Jordon becomes the active Arm.
The rift opens over the next 70~80,000 and the bottom drops 150~200 feet from the Gulf Aqaba to about OTL location of Beirut.
However this doesn't stop travel/migration, as the Sea level is about 300 feet lower than now due to the Ice Age.
Far to the East about 15,000 years BP the Nile [larger amount than OTL] takes a dogleg from Cairo east along the Qassian Depression reaching the Sinai just north of the Great Bitter Lake.
Over the next couple thousands years, this increases the size of Bitter Lake & scours out a channel between the Lake and the Gulf of Suez.
The enlarged Lake creeps north along the low [OTL 10~20 feet above now sea level.] depressions between the Lake and the Med Coast. Scouring a slight Channel.
About 12,000 BP the Ice Age ends, The Nile/Suez Arm drys up and return North toward the Med. and the Sea Level begins to Rise.
The rising Sea fills in the Gulf Aqaba and moves north along the new rift , to the North the Med begins moving south from Beirut, till they meet at the Sea Galilee.
To the East the Rising Sea moves up the Bitter Lake Channel into the Bitter Lake, and then Over the Slight Channel to the Med.
By 8000 BP the sea level has stabilized with the Sinai as a large semi desert Island separating Africa and Asia.
about 6000 BP
Adam, a illegal Blacksmith, with his wife Eve and sons Abel & Cain, lead their friends and Family West,
They are fleeing the local authorities in Mesopotamia, that are trying to keep Iron Working a Military secret.
Arriving at the Jordon Straits, they build rafts to transport their herds [Horse, Cattle, Sheep, Goat] across arriving on the North end of Sinai Island.
In time they will form two Tribal Nations, that will be the power houses on the Island.