Aroko was a way by which pre-literate Yorubas used to send message over long distance in the olden days. It is done by sending some symbolic items to the person for whom the message was meant through a third party; and the message would be understood by the receiver.
For an instance in December 1854, the Awujale of Ijebu sent such a parabolic message to Rev. David Hinderer who was then resident in Ibadan. The Aroko he sent to him was this: ten cowries strung together and a seed of the orange fruit. The meaning of the Aroko is this: come, it is well. Can you spot the correlation between the items sent and its meaning?