Group Companies

I would like to Group companies by region, so that the Technicians/managers for that region  will have visibility of all the companies in their region only.
eg. customers globally can raise tickets, I will have visibility of all of these tickets as an administrator and my teams around the globe will action them as they are created, However the Technicians/teams in Asia would like to have visibility of all tickets raised in the Asia/Pac region (multiple companies) but they should not be able to see or report on any European tickets, Likewise for USA, the Technicians/teams in the US would like to see all raised tickets in their region, from all the different Customers (companies) that submitted tickets, but they should also not have visibility of Europe or Asia.
Many Thanks