During Abbasid rule, some individuals from the tribe embraced Islam and were given governorships in parts of the Caliphate. By the mid-9th century, much of the Taghlib converted to Islam, partly as a result of the persuasion of the Taghlibi governor of Diyar Rabi'a and founder of al-Rahba, Malik ibn Tawk. Several Taghlibi tribesmen were appointed governors of Diyar Rabi'a and Mosul by the Abbasids. In the early 10th century, a Taghlibi family, the Hamdanids, secured the governorships of these regions, and in the 930s, the Hamdanid leader Nasir al-Dawla formed an autonomous emirate out of Mosul and Jazira. Likewise, in 945, his brother, Sayf al-Dawla, created a northern Syrian emirate based in Aleppo. The Hamdanids ruled both of these emirates until their political demise in 1002.
The Banu Taghlib were originally a Bedouin (nomadic Arab) tribe that inhabited the Najd. The tribe was named after its progenitor Taghlib ibn Wa'il, also known as Dithar ibn Wa'il. The tribe belonged to the Rabi'ah confederation and thus traced its descent to the Nizar branch of the Adnanites. Their full genealogy is as follows: Taghlib/Dithār ibn Wāʾil ibn Qasit ibn Hinb ibn Afṣā ibn Duʿmī ibn Jadīla ibn Asad ibn Rabīʿa ibn Nizār ibn Maʿadd ibn Adnān. Their rival and brother tribe was the Banu Bakr ibn Wa'il.
Information about the Taghlib's branches were in large part based on the records of the pre-Islamic Taghlibi genealogist al-Akhzar ibn Suhayma. Taghlib ibn Wa'il had three sons, Ghanm, Imran and al-Aws. However, in Arab genealogical literature, only the descendants of Ghanm ibn Taghlib are discussed extensively. From Ghanm came the al-Araqim, which referred to the descendants of six sons of Bakr ibn Hubayb ibn 'Amr ibn Ghanm, all of whom had eyes that resembled those of arāqim (speckled snakes; sing. al-Arqām). The al-Araqim were the most important group of the Taghlib and nearly all of the genealogical history of the Taghlib centers around them. The six divisions of the al-Araqim were the Jusham (the largest), Malik (second largest), 'Amr, Tha'laba, al-Harith and Mu'awiya. Because of their size and strength, the Jusham and Malik were collectively referred to as al-Rawkān, which translated as "the two horns" or "the two numerous and strong companies". The smaller 'Amr division of the al-Araqim was known as al-Nakhābiqa.
From the Jusham division came the Zuhayr branch, from which several large sub-tribes descended, including the 'Attab, 'Utba, 'Itban, 'Awf and Ka'b lines; all of these lines were founded by the eponymous sons of Sa'd ibn Zuhayr ibn Jusham. The 'Attab, 'Utba and 'Itban sub-tribes formed the al-'Utab grouping, while the Awf and Ka'b sub-tribes formed the Banu al-Awhad. Another leading Zuhayri sub-tribe was the al-Harith, whose eponymous founder was a son of Murra ibn Zuhayr. The Malik division also bore numerous tribal groupings, including al-Lahazim (descendants of Awf ibn Malik), al-Abna' (descendants of Rabi'a, 'A'idh and Imru' al-Qays, all sons of Taym ibn Usama ibn Malik), al-Qu'ur (descendants of Malik's sons Malik and al-Harith) and Rish al-Hubara (descendants of Qu'ayn ibn Malik). The Hamdanid dynasty traced its descent to the Malik division via their ancestor 'Adi ibn Usama ibn Malik.
In the pre-Islamic era (pre-630s), the Taghlib were among the strongest and largest Bedouin tribes in Arabia. Their high degree of tribal solidarity was reflected in the large formations they organized into during battle. The tribe was involved in several major battles during this period. As early as the 4th century CE, the Taghlib were within the sphere of influence of the Persian Sasanian Empire and their Arab clients, the Lakhmid kings of al-Hira. It is mentioned during this time that the Sasanian king Shapur II sent Taghlibi captives to live in Darin and al-Khatt, both in the region of Bahrayn.