Hi Tony

There are some existing plugins that go part of the way

• course enrolment - external database (position assignment)
• user authentication methods - external database

There are also some scripts that have been developed for clients and an official importer that is being worked on see https://totara.community/mod/forum/discuss.php?d=16994#p6027 for more details. Kineo UK have also developed an import by csv script.

Craig