In Paradox's 3rd Dev Diary for the content of the Sub-Saharan region, we are given a look at the Horn of Africa - at the realm of Ajuuraan, and the gameplay it will bring, to be more precise.
Ajuuraan is one of the Somali clans in the Horn and is known for its impressive irrigation system, for its unique position as a theocratic clan state, as a trading nation, which had its merchants active in India and Asia, and even as a winner against Portuguese aggression. The mission tree for Ajuuraan reflects these traits, focusing on both the military strength and the trade power it possessed.
The most left row focuses on the trade aspect of Ajuuraan. A theme of this row is the importance of Mogadishu as a center of trade and its minted currency. After annexing Mogadishu you get access to the "Gain Gold Access" mission. The requirements of it seem easy enough: just have a gold province. However, the mission can also be completed diplomatically by allying and having 100 opinion with a country that happens to have a gold province.
If you finish the mission diplomatically, your ally will receive an event, which will ask them to supply Ajuuraan with their precious metal. They either can choose to refuse, giving mercantilism for the ally, or accept the deal, reduce their own Global Trade Power by 5%, but increase Goods Produced by 5% and reduce the inflation by 0.05 for 25 years. In exchange, Ajuuraan will receive an acceptance or refusal event. In case of acceptance, you get 0.25 years worth of income, increased Global Trade Power by 10%, increased Trade Power Abroad by 25%, and increased inflation of 0.05 for 25 years.
The Trade Power Abroad might seem a little bit off, but it will come in handy for the next mission "Trade with India", where you need to have 5% Trade Power in any of the Indian trade nodes. Achieving this mission will trigger the "The Merchants of Ajuuraan" event for all countries which have their capital in India.
Afterward your trade row branches into three directions, where you need to have an active merchant in Beijing, good relations with Dong Kinh, and have 5% trade power in the Moluccas. My personal favorite is the event for the Emperor of China when you finish the mission "Trade with the Dragon".
The right side of the mission tree is more focused on the military and the conquest with the end goal of consolidating your region.