AWS Certificate Manager (ACM) Private Certificate Authority (CA) is now available in the Middle East (Bahrain) region. This regional expansion extends the availability of ACM PrivateCA across the globe, increasing the number of regions to 19.

from Recent Announcements https://aws.amazon.com/about-aws/whats-new/2019/10/aws-certificate-manager-private-certificate-authority-available-middle-east-region/