Adal comes to control the important trading routes from the highlands to the port of Zeila, thus posing a threat to Ethiopia's commerce and, at times, to Christian control of the highlands.

Although the Christian state is unable to impose its rule over the Muslim states to the east, it is strong enough to resist Muslim incursions through the fourteenth century and most of the fifteenth.

As the long reign of Zara Yakob comes to an end, however, the kingdom again experiences succession problems.

It is the monarchs' practice to marry several wives, and each seeks to forward the cause of her sons in the struggle for the throne.

In those cases where the sons of the deceased king are too young to take office, there can also be conflict within the council of advisers at court.

In a polity that has been held together primarily by a strong warrior king, one or more generations of dynastic conflict can lead to serious internal and external problems.

Only the persistence of internal conflicts among Muslims generally and within the sultanate of Adal in particular prevents a Muslim onslaught.