The First Persian Empire was the largest and best organized empire of the ancient world, connected by 1,500 miles of roads, as well as the first to offer mail service.

The First Persian Empire is part of the Super Science Facts series that engages readers in grades 5 to 12 with fun science facts and colorful images on every page to support comprehension. The series covers Physical Science, Life Science and Social Sciences in individual sets. The minimal-text format (1,700 to 2,000 words per book) introduces content vocabulary defined in context and repeated in a glossary.