This is because its author has died, and 50 years have passed since publication, by the virtue of Articles 1653 and 1670 of the Eritrean Civil code. In the case of anonymous works, the publisher becomes the copyright holder per Article 1667.
Eritrean photographs are only protected if they are part of a collection or book, or bear the name and address of the author or their agent. In all other cases, photographs are not protected by copyright (Article 1662).