How to link a territory to a user?

How to link a territory to a user?

We have a new user who is based in Singapore, is there a way for when he adds a new contact for these to be automatically assigned to the Singapore territory? Currently everything is defaulted to be assigned to the UK territory as most of our other users are based in the UK. We don’t want to restrict him from seeing the UK contacts though, but we just need to be able to differentiate between his contacts and the rest of the UK's. Please help.