How to config one domain, mutiple tenants?

Based on privacy protection, I have three tenants
brand.us.auth0.com
brand.eu.auth0.com
brand.jp.auth0.com

My unified login domain name for global users is:
auth.brand.com
How to configure all of these

When users from different countries access the domain
How to assign them to different tenants?

Hi @jason8,

Unfortunately, it’s not possible to configure a single custom domain across multiple tenants.

For now, we only support using a single custom domain per tenant. Therefore, if you have multiple tenants, each would need its own separate custom domain.

Please refer to the Custom Domains documentation.

Thanks,
Rueben