Original: Having been bred from a Welsh Terrier and an Otter Hound , the breed has also been called the Waterside Terrier , because it was bred originally to hunt otters in and around the valleys of the River Aire which runs through Airedale .
Simplified: It traditionally was called the '' King of Terriers '' because before the creation of the Black Russian Terrier by the NKVD , the Airedale was largest of the terrier breeds .