only set players can enter a reagon
/rg flag <region_ID> entry deny
/rg flag <region_ID> entry -g vip
Deny entry to anyone who is not a member (or owner).
/rg flag <region_ID> exit deny
/rg flag <region_ID> exit -g nonowners
Deny exit to anyone who is not an owner.
/rg addmember <region_ID> g:Builder
/rg addowner <region_ID> g:VIP
Add the "Builder" group to members and the "VIP" group to owners.