Ancient Persian refers to the language and culture of the Persian Empire, which flourished from the 6th century BCE to the 4th century BCE. The primary language, known as Old Persian, was used in inscriptions and royal decrees. It is part of the Indo-Iranian branch of the Indo-European language family and is distinct from modern Persian, or Farsi. The Persian Empire, founded by Cyrus the Great, was known for its vast territory, which included parts of Asia, Africa, and Europe. It was characterized by a sophisticated administrative system, impressive architecture, and cultural achievements, such as the creation of the Royal Road for trade and communication.