Simplify the following text for a Grade 7 native English-speaking person.
Original: The Nottingham Robin Hood Society was originally formed by Robin Hood historian Jim Lees and two Nottingham teachers Steve and Ewa Theresa West in 1972 .
Simplified: Robin Hood is said to have lived in Sherwood Forest , which extended from the north of Nottingham to the north side of Doncaster , Yorkshire . Hood 's main opponent was the Sheriff of Nottingham .