The funny part about it, they are even trying posit before that the southern coast was colonies by foreigners. I can guarantee you no one would settle on the coast from the outside because it's mostly just surrounded with sand dunes. And you saw zero outsiders make settlements on the coast in the 19th-20th century either.
So the coast was set up mostly as commercial outlets from the production of the interior. The interior producers would settle and bring their produce to trade with.
The purple coloured areas in the Somali peninsula are called the Somali acaci–commiphora bushlands and thickets. It's an ecoregion mostly made up of semi-arid tropical grasslands, savannas, and shrublands.
So it is rich in woodlands and vegetation throughout.
Kismayo is a perfect example because it was originally a coastal fishing village inhabited by Garre-Tunni-Bajun that was transformed into a trading port founded by Harti-Majerteen traders in the 19th century and it's connected to the production of the fertile Waamo region i Juba Hose