Both versions of the Book and the similar Kawkab al-durriya li-akhbār Ifrīqiya have nearly identical accounts down to the 17th century, because they relied either on the same written sources or the same oral traditions.
James Ritchie and Sigvard von Sicard give five reasons why the early history in the Book "may be more than mere fancy or legend", while acknowledging that further archaeological and historical research is needed to go beyond surmise.
[10] It describes the tribes of the Kushūr, a Mijikenda people who lived in Shungwaya by the Juba River until forced south by the migrating Oromo; several waves of Arab immigration to East Africa, both before and after their conversion to Islam; and the arrival of the Portuguese under Vasco da Gama.
[15] The beginning of the redaction in manuscript K goes as follows: In the Name of God the Merciful the Compassionate, and to him we call for help, this is the Book of the Zunūj and information about them on the shore of the Indian Ocean towards the West.
Praise be to God the Creator and Maker, the Loving, Possessor of Excellence, Generosity and Liberality, Who made for His creatures colours, white, red and black, and gave precedence to some over others in respect of lordship, extent [of rule] and happiness, and decreed for him whose father prayed against him blackness of face both for him and his offspring, and that they should be slaves to the offspring of his two sons.
And so we have summarized information about the Zunūj on the shore of the Indian Ocean towards the West, and the Equator, to make clear the Zanji inhabitants whom God created in it, who were on the Juba, that is, the Kushūr in the original Arabic speech and the WaNyika in the Swahili language; and information about the Arabs who came to the Zanj country and built houses in the districts and towns and villages, and dwelt in them from the time of the jāhiliyya .