Banu Hilal

The Banu Hilal ( or ) was a confederation of Arabian tribes from the Hejaz and Najd regions of the Arabian Peninsula that emigrated to North Africa in the 11th century. Masters of the vast plateaux of the Najd, they enjoyed a somewhat infamous reputation, possibly owing to their relatively late (for the Arabian tribes) conversion to Islam and accounts of their campaigns in the borderlands between Iraq and Syria. With the revolutionary movement of the Qarmatians in Bahrayn and Oman, they participated in the pillage of Mecca in 930. When the Fatimid Caliphate became masters of Egypt and the founders of Cairo in 969, they hastened to confine the unruly Bedouin in the south before sending them to Central North Africa (Libya, Tunisia and Algeria).
Origin.
According to Arab genealogists, the Banu Hilal were a sub-tribe of the Mudar tribal confederation, specifically of the Amir ibn Sa'sa'a. The Hilal were very numerous, effectively a nation divided into its own sub-tribes, of which the most notable were the Athbaj, Riyah, Jusham, Zughba, Adi, Qurra, and Ma'qil.
History.
Its original habitat, like that of its related tribes, was the Nejd, and its history during pre-Islamic times is bound with that of its parent tribes. The Hilal likely did not accept the rule of Islam until after the Battle of Hunayn in 630, but they also did not join in the Wars of Apostasy that followed Muhammad's death in 632. 
Migration to Egypt.
The tribe does not appear to have played any significant role in the early Muslim conquests, and for the most part remained in the Nejd. Only in the early 8th century did some of the Hilal (and the Banu Sulaym) move to Egypt. Many followed, so that the two groups became numerous in Egypt. During the Abbasid Caliphate, the Hilal were known for their unruliness. 
In the 970s, the Hilal and the Sulaym joined the radical sect of the Qarmatians in their attacks on the Fatimid Caliphate, which had just conquered Egypt and was pushing into Syria. As a result, after his victory over the Qarmatians in 978, the Fatimid caliph al-Aziz () forcibly relocated the two tribes to Upper Egypt. As they continued to fight among themselves and pillage the area, they were prohibited from crossing the Nile River or leaving Upper Egypt.
Migration to the Maghreb.
According to Ibn Khaldun, the Banu Hilal were accompanied by their wives and their children when they came to the Maghreb. They settled in Tunisia after winning some battles against some Berber tribes, eventually going on to coexist with them.
Ibn Khaldun described their genealogy, which consisted of two mother tribes: themselves and the Banu Sulaym. In Arabia, they lived on the Ghazwan near Ta'if while the Banu Sulaym attended nearby Medina, sharing a common cousin in the Al Yas branch of the Quraysh. At the time of their migration, Banu Hilal comprised six families: Athbadj, Riyah, Jochem, Addi, Zughba, and Rbia.
Abu Zayd al-Hilali led between 150,000 and 300,000 Arabs into central North Africa, who assimilated and intermarried with the indigenous peoples. The Fatimids used the tribe, which began their journey as allies and vassals, to punish the particularly difficult to control Zirids after the conquest of Egypt and the founding of Cairo. As the dynasty became increasingly independent and abandoned Shia Islam, they quickly defeated the Zirids and deeply weakened the neighboring Hammadid dynasty and the Zenata. Their influx was a major factor in the linguistic, cultural Arabization of the Maghreb and in the spread of nomadism in areas where agriculture had previously been dominant. Ibn Khaldun noted that the lands ravaged by Banu Hilal invaders had become completely arid desert.
The Banu Hilal later came under the rule of various subsequent Berber dynasties, including the Almohad Caliphate, Hafsid dynasty, Zayyanid dynasty and Marinid dynasty. Finding their continued presence intolerable, the Almohad Caliphate defeated the Banu Hilal and forced many of them to leave Tunisia and settle in Morocco. Upon the arrival of the Turks, the Banu Hilaleen rose against the Ottoman Empire alongside Berbers in the Aurès region and south of Algeria.
Social organization.
Originally, the Banu Hilal embraced a nomadic lifestyle, rearing cattle and sheep. Despite several tribes living in arid and desert areas, they became experts in the field of agriculture. The Hilaleen do not embrace any specific ideology and are not very conservative, though the majority of the population does embrace Islam. Initially Shia, after their conquest of the Sunni Maghreb majority of Banu Hilal converted to the Maliki school of Sunni Islam. Other tribes Arabized the Berbers to a considerable extent in Algeria, where intermarriage occurred frequently during their shared history.
Taghribat Banu Hilal.
The accounts and records that the folk poet Abdul Rahman al-Abnudi gathered from the bards of Upper Egypt culminated in the Taghribat Bani Hilal, an Arab epic describing the journey of the tribe from Arabia to the Maghreb. The tale is divided into three main cycles. The first two bring together unfolding events in Arabia and other countries of the east, while the third, called "Taghriba" (march west), recounts the migration of the Banu Hilal to North Africa.