Their re-examination has given rise to much speculation about how these medieval African coins came to Australia .
Four of the coins were found to have come from the Dutch East India Company , while the other five were determined to be from the Kilwa Sultanate in Tanzania .
Four 's re-examination has given rise to much speculation about how these medieval African coins came to Australia .
Four of the coins were found to have come from the Dutch East India Company , while the other five were determined to be from the Kilwa Sultanate in Tanzania .