Synchronising Groups between two different systems

Hello.  What's the recommended general method for synchronising groups between two different systems?  I've read through the documentation and see some information about syncing between two systems of the same type (like two AD forests), but not about going from two different systems.  Also in the documentation, there is some description about doing this with users by going via Employees but there doesn't seem to be an analog for groups that I can see.

Thanks