They are from Port Harcourt, Nigeria.
At the time I got mine in 1998 there was N2.25 Niras to the US dollar. I also have the N5 & N25.
The Casino was open 1981 to 83.
I got mine from Harvey Fuller who got them from a high ranking goverment official that oversaw the casino. The Official was living in LV and was having a yard sale. Harvey haunted yard sales. He gave Harvey a bunch of his business cards from 1981. I have one somewhere in my files. I am pretty sure he was the President of Nigeria. I am need to look for the card.