The naira is the official currency, the Central Bank of Nigeria is in charge of the currencies in Nigeria.
This article contains the history of the pictures on the ten naira note, the pictures contains Fulani milk maids.
The picture at the back of the 10 naira are photography of two Fulani ladies hawking cow milk with their calabash. It has been discovered that the pictures were real photography of human being it was snapped by an English photographer called John Wilfrid Hinde.
His real style of photography influenced the photograph John Wilfrid Hinde took the picture of the Fulani milk maids between 1960 and 1970