The veracity of Vassa's account of his early life has been called into question by certain scholars, notable among whom is Vincent Carretta. Carretta argues - among other things - that Vassa's place of birth is listed as South Carolina on his baptismal record and on his naval record. He accuses Vassa of making up an African history and an African name. Yet other scholars, including Lovejoy, have counter-argued that there is enough evidence in his narrative to prove that Vassa did indeed come from Africa when he claimed he did. Lovejoy points out, among other things, that Vassa was circumcised at a time when circumcision was not practised in Anglo-America, and mentions the practice at least five times in a book directed at an audience that would have found the practice repugnant. Vassa, also always identified as African in all his letters to newspapers. Vassa was aware of the limitations of his memory and makes this admission in his autobiography, acknowledging that his recollections were helped by information he got from other Igbo people he encountered. One would expect that if he were only pretending to be African, that he would not have openly and willingly admitted to this. Yet, he is detailed in his recounting of the particular rituals and traditions of his own people.  
His approximation of Igbo terms is close enough to still be understood centuries later, and he refers to 'mahogany-coloured men from the south-west of us: we call them Oye-Eboe' (Equiano, p. 51). Certain Igbo communities around the present-day Delta/Riverine area refer to the Igbo of the south-east as $O(n)$ ye Igbo. Vassa's transcribed Igbo also sounds like the dialect spoken in those areas. The men who calculated time in his place of birth were called ab-affoe-way-cab. I have not yet found the word this is supposed to replace. However, in Igbo, afo/abo is 'year'. In certain Delta Igbo dialects, wa translates to 'they' and kab to 'foretold' or 'said'.