Harun al-Rashid (English: Aaron the Upright, Aaron the Just, or Aaron the Rightly Guided) March 763 or February 766 — 24 March 809) is the fifth Arab Abbasid Caliph.

His rule encompasses modern Iraq.

His actual birth date is debatable, and various sources give dates from 763 to 766.

Al-Rashid rules from 786 to 809, and his time is marked by scientific, cultural, and religious prosperity.

Islamic art and Islamic music also flourish significantly during his reign.

He establishes the legendary library Bayt al-Hikma ("House of Wisdom").

Since Harun is intellectually, politically, and militarily resourceful, his life and his court have been the subject of many tales.

Some are claimed to be factual, but most are believed to be fictitious.

An example of what is claimed to be factual, but is not, is the story of the clock that was among various presents that Harun had sent to Charlemagne.

The presents were carried by the returning Frankish mission that came to offer Harun friendship in 799.

Charlemagne and his retinue deemed the clock to be a conjuration for the sounds it emanated and the tricks it displayed every time an hour ticked.

Among what is known to be fictional is The Book of One Thousand and One Nights, which contains many stories that are fantasized by Harun's magnificent court and even Harun al-Rashid himself.

The family of Barmakids, which had played a deciding role in establishing the Abbasid Caliphate, decline, gradually during his rule.