Below you will be working through an Example of how this can be configured for a Company spread across two Countries, Country A and Country B. 

The rules will be as follows:

• Users in Country A can Read & Modify People Records assigned to Users in Country A but not Country B
• Users in Country B can Read & Modify People Records assigned to Users in Country B but not Country A

Before you start configuring the Permissions, you need to make sure that you have User Groups in your database for Users in Country A & Country B.

Once you have done this you need to set up the Permissions for these Groups from Start > Configuration > Users & Security > Permissions

The first thing you will need to do is create a new Ruleset, to do this select Manage Rulesets:

And then select New Ruleset:

You will only need to create a single Ruleset, which will contain the Permissions for both Country A Users and Country B Users. This will provide your User Groups with access to items that they Own such as below:

You can now save and close the Ruleset and now add a Sharing Policy, by selecting Add Sharing Policy:

From this view you will need to fill out the Form and apply a new Ruleset. As you are using People Records, in this example you will need to create a New Sharing Policy that will look like below:

This means that any People created by Everyone will only have the sharing permissions of that Country Ruleset which you recently applied. Providing that all of your Users are in either Country A or B then this will affect all of your Users and if there are additional Countries that you do not want to limit then you will need to set the Created By to be the specific User Group such as:

Now you have created the Ruleset and Sharing Policy you will need to update the Sharing Permissions which can be done through a Bulk Action on the Landing Page of the specific record type:

Once the Permissions have been recalculated the new Sharing Policies will take effect and a User in Country A will no longer be able to see any Person Record that is assigned to anyone in the Country B User Group and vice versa.