An ethnologist is someone that deals with animal behaviour and that is a huge group.
I know of the Parelli school which came from Ray Hunt and Buck Brannaman and Tom Dorrance. You can identify the schools from the learning material and technique but overall they are all pretty similar because they all start from the horse behaviour.
You can look out at Andy Booth's website, there're many formations there!
Juan Vendrell (Spain), Scarparti (Argentina), Manu Godin (France), Tink Elordi (USA), Joe Wolter (USA), and so many others! :)