Our war begins due to dynastic fallout in the then-independent kingdom of Aksumite Arabia. In 570, Abraha, the Aksumite general who rebelled against Kaleb and created his own independent kingdom, died. Abraha struggled to designate a clear heir before his death. While he had many sons, the two who would play the most consequential role in the upcoming struggle were named Masruq and Madi Karib (sometimes also referred to by the name Yaksum).
Note: The identity of Madi Karib is sometimes contested. The mainstream scholarly opinion is that Madi Karib and Yaksum are two names for the same person, with Karib being the name used by Arabs and Yaksum being the one used by Ethiopians. However, it is worth noting that some scholars believe otherwise, and that Yaksum and Madi Karib are two distinct people. This podcast endorsed the mainstream view as espoused by Glen Bowersock in his book The Throne of Adulis: Red Sea Wars on the Eve of Islam. It's also worth noting that many accounts of the period seemingly conflate the actions of Madi Karib and the legendary king Sayf. However, because of his poor attestation in reliable histories outside of the History of Tabari, we opted to side with Bowersock's perspective that Sayf died before the invasion commenced, and that the actions attributed to Sayf during and after the invasion were instead performed by Madi Karib.
Where things went sour between two most prominent sons of Abraha is up for debate. Their struggle may have originated out of a cynical desire for the throne, or it may have been based on a staunch disagreement regarding how they would engage in diplomacy with Aksumite Africa. Masruq favored a policy of reconciliation, and sought to return Aksumite Arabia to a tributary status. Again, his motivations for why are unclear. Reconstructing the history of Masruq and Karib's feud is a bit like asking questions about the chicken and the egg. Did Masruq submit to Aksum for help against Karib's rebellion? Or did Karib rebel because Masruq submitted to Aksum? In the podcast, I chose to make something of a compromise between these views, arguing that Masruq was already planning to submit to Aksum, but that Karib's rebellion made the need to do so more urgent. However, Karib's early attempt to seize the throne failed, and he was sent into exile.