Christianity and Islam both facilitated the growth of sub-Saharan African kingdoms, both in the East and West. In Aksum, trade was "essential" to the kingdom's development in northwestern Ethiopia, as it was strategically located geographically on a major trade route linking India with the rest of Africa, the Mediterranean, and Arabia (p. 205). Unlike many other kingdoms in Africa, the Aksum fully embraced Christianity within the first few centuries of the religion's dissemination. Aksum was in fact one of the earliest Christian empires, operating fully independently from Rome, where Christianity would take root and become the hub of European cultural, economic, and political life. In its heyday, the kingdom of Aksum depended on the Christian mythos and ethos to sustain its centralized power under King Ezana, who declares his power to be God-given in his stele: "he has given me strength and power and favoured me with a great name through his son in whom I believed," (p. 207). King Ezana's stele is also written in language style akin to Biblical texts, creating an indelible cultural link between what would become Ethiopia and the Middle East. That link had already been firmly entrenched given the ethnic, geographic, and linguistic ties between Aksum/Ethiopia and the Middle East. As a result, King Ezana was able to conquer the entire region, from Nubia in the northeast to the top of the Arabian Peninsula. The Aksum Empire extended into the Sudan and Arabian Peninsula at its peak. Furthermore, Christianity was able to remain entrenched in Ethiopia even after Aksum floundered, differentiating Ethiopia from its neighbors throughout the rest of the region's history. Part of the reason for the resilience of Christianity in the region is that it was fully entrenched, not a superficial cultural icon with temporary value for the people but an integral part of their identity, heritage, and language. Its strategic geographic position also enabled Aksum to remain fairly wealthy even during its decline....

The Christian religion influenced the growth of power and economic growth in the region, creating some tension between Aksum and its neighbors as Islam came to the fore. Those tensions would influence political and economic decisions thereafter. Just as Christianity provided a driving force during the Kingdom of Aksum, leading Ezana to conquer neighboring lands, Islam likewise became a unifying and potent force throughout both North Africa and Sub-Saharan Africa. Trade routes established by Arabs, who had the only means by which to traverse the otherwise impenetrable deserts of Africa, ensured that Islam would spread its influence in Africa relatively rapidly and much more rapidly than Christianity. Just as trade routes provided the economic power enabling Aksum to expand, so too did trade routes across the Sahara and into West Africa and North Africa allow otherwise small kingdoms to flourish. Moreover, the ways rulers used religion to bolster their legitimacy remains a common thread throughout the kingdoms of Africa.
Centuries after the decline of the Roman Empire, the resulting religious, cultural, and political vacuum in North Africa permitted the Islam to easily infiltrate its diverse regions. However, the most important means by which Islam spread throughout North Africa was via the trade routes that had already been established by caravanserai and which were becoming more robust. As Islam spread from the Arabian Peninsula, so too did the flow of goods and ideas on the caravanserai trails dependent on the use of the Arabian camel (p. 208). Wealth and power flowed together simultaneously along the caravanserai, speeding up as early as the 7th and 8th…