Harb (Arabic: حرب‎) is a large confederation of Sunni clans in the Arabian peninsula. There is no official tribe population count but it is estimated to be approximately four million in Saudi Arabia. It is originally a Qahtani tribe. Several authentic sources on Arab tribes genealogy state that the great-grandfather of Harb tribe is Harb ibn Saad ibn Saad ibn Khawlan ibn Amr ibn Qadha'ah ibn Himyar ibn Qahtan. Harb tribal lands extend from the Red Sea coast in Hijaz (Western Part of Saudi Arabia) to the heart of Najd in the central region of Saudi Arabia, and from North the Harbi lands extend from Madinah (a holy city for Muslims) to Al Qunfudhah in the south. The tribe's reach extends to other countries like Kuwait, Iraq, Egypt and UAE .

The origins of Harb tribe came from the 2nd century of the Islamic calendar, when Qahtani tribes emigrated from the south of Arabian Peninsula to Hijaz around 131 AH for water and land space after some battles with their cousins Banu Ar-Rabi'ah bin Saad. As a result, this caused several tribal conflicts with the native and mostly Adnani Arab tribes of Hijaz such as Juhainah, Inazah, Muzianah, and Sulaim over land and water. After around three centuries in Hijaz, Harb tribe became a dominant tribe in the heart of Hijaz with territories surrounding the holy city of Madinah. It is important to note that Harb now, like many other Arabian tribes, is a federation of tribes and families, a good example is that Muzaynah in Saudi Arabia are considered from Harb but it is well known that it was a tribe of its own with a known presence in Hijaz in the Pre-Islamic Arabia as well as the time of the Prophet Muhammed i.e. before the origin of Harb tribe in Hijaz.