The Robin Hood stories, in the form we usually know them now date from a later period than they actually occurred, like the Arthur legends. They owe much to th era of chivalry and are essentially adult fairy stories and fulfilled at the time the same function that Westerns fulfilled and Star Trek and Star Wars still do now. It's a good framework for storytelling.
The earliest influence for me is the Biblical story of David, who while on the run from King Saul operated with a group of 'Mighty Men' and protected isolated landowners and families from predators and injustice. They supported him by giving the mighty men food and supplies. That's how he met his second wife Abigail. The mighty men became his inner group of army warriors and leaders when he became King.
Or was this , perhaps the template for DOC Savage?
Cheers!
Link to the book:
Thriller Picture Library 166