Simplify the following text for a Grade 6 native English-speaking person.
Original: Its early ancestors are the bull and the terrier , it used to be called the Blue Paul Terrier . Then , in around the 1930s , dogbreeders bred it with the Pitbull terrier and it became the American Staffordshire Terrier
Simplified: They are not to be confused with the Staffordshire Bull Terrier .