There is no real evidence to certify that Cardoza was born in the Basque country between Spain and France. In reality, there really is no proof that he actually existed at all. The stories of his exploits have come down to us as an oral tradition. I may be the first person to try and chronicle some of the events in his life. I make no claim that any of what I am going to say bears any relation to the truth.
The history of this wondrous character seems to begin in Spain right after Columbus sailed to the new world. There are documents that I have seen in a museum in Cadiz that imply that Cardoza had something to do with raising funds for Columbus’ trip. The fairy tale that Queen Isabella hocked her jewels to fund the operation is just so much balderdash.
Although Columbus probably asked Isabella and Ferdinand, they had too many problems of their own combing Aragon and Castile into one unity, to bother with helping this nutty seaman. The documents that I read had to do with payment upon return to Spain. There was a kind of I.O.U. from Christoforo Columbo to one Senor Zanzibar Cardoza Morales, that would come due when treasures would accompany the Pinta the Nina and the Santa Maria’s return to Spain. It is quite clear that Cardoza was going to get mucho dinero from this investment.
From 1492 onward, I cannot find any information about Cardoza. There are many stories that he was a mercenary in many wars at that time. Somehow he was involved in the crises that arose from the establishment of the Protestant religions just after Martin Luther created his disturbance. Cardoza seemed to sell his services to whatever side paid him the most money.
One of the difficulties of putting all of this together is that Cardoza’s legend extends over a number of centuries. It is certainly impossible to believe that he lived such a long a fruitful life beyond mortal longevity. If any of the stories that are told, that begin in 1492 and continue to the end of the 18th century, Cardoza was immortal, a vampire, or there were countless Cardozas (as with the dread pirate Roberts).
Zanzibar is not a Basque name. I am not even sure how the name came to be in the Basque country. There are a number of Z names for boys, but none close to Zanzibar. I am not even sure that Zanzibar was the name of the part of the African continent at that time. Safe to say that the legend is pretty clear and that was his name in 1492.