Final answer:
West Africa was the region most affected by the Trans-Atlantic slave trade, experiencing significant demographic, social, and political transformations as a result of the high demand for slaves in the Americas.
Step-by-step explanation:
The most affected region by the Trans-Atlantic slave trade was West Africa. This area saw multiple changes during the slave trade era, including a drastic decline in population due to the demand for slaves in the Americas. Slave traders penetrated deeper into the African continent as coastal supplies reduced, leading to wars and slave raids that exacerbated the demographic crisis. Additionally, this spurred the rise and fall of various states, some owing their existence to the slave trade economy.
For instance, the Kingdom of Dahomey is a poignant example of African participation in this trade, which saw the transport of at least ten million Africans through the Middle Passage, with high mortality rates. It's important to note that while West Africa was a major source for the Trans-Atlantic trade, the Swahili coast on the East African side was also engaged in slave trade, sourcing slaves from the interior of the continent. However, these were two largely separate systems.