Can I display sales territory change history in the UI?

No, but you can create a report of the changes instead. The Change History subtab doesn't display sales territory changes. However, you can enable audits of territory management using the setup task Manage Audit Policies in the Setup and Maintenance work area, and then view the report in the Audit Reports work area, which is available in the Navigator, Tools section.

To set up auditing, you must be a setup user, a sales administrator, or have another job role that includes the Manage Sales Audit Policies privilege (FND_MANAGE_SALES_AUDIT_POLICIES_PRIV).