Possible to hide Communits c/o Yammer county-by-county?

Question

Just trying to establish Yammer in our enterprise. Situation: globally active company. Some parts already use Yammer Is it possible to have a clear distinction to the other countries. Means the established groups should only bee seen within one country. Problem: across the hole globe the staff uses one Domain. Is there another way as to set up a Community as aprivate Community, which would not make any sense if you wish to have an internal knowledge transfer, and no One can see the esablished Communitoes, as the are hidden for others. Thank you very much in advance for your assistance!