As I am working on a chapter about gender and horses in Early Islamic Arabic texts I read my way through numerous academic articles and books about genealogy, gender and politics in Early Islam as well as pre-Islamic times.
In the work of Majied Robinson on marriage within the Quraysh tribe between 500-750 CE it is explained that concubinage was not a foreign idea to the family of Prophet Muḥammad. Interestingly, children of these concubines were classified as Hajīn, a term very well known within the Arab horse breeders community.
An interesting observation is that people classified as Hajīn were not regarded as lesser in Umayyad times, in fact the Nasab Quraysh tells us that they had better chances for a good marriage than the children from wives.
However in the Abbasid era, the concept of Hajīn became slightly altered, as genealogists and philologist facilitated the consolidation and retrojection of Arab identity and Hajīn became the term for children of a non-Arab mother. Whether this means that Umayyad concubines were often considered non-Arab in retrospect by Abbasid era writers is unclear, as the back projection of Arab identity onto pre-Islamic tribal communities and families was very inclusive and there is no evidence that in Umayyad times they were seen as ethnically different or even valued less. Statistics show they often married well.
Interestingly the Abbasid definition of Hajīn, a child of a non Arab mother by an Arab father, leaves out the original requisite of marriage vs concubinage and pushes for the idea that Hajīn is inferior to Arab. But it is in this form that the concept also appears in the system of classification of horses in medieval Arabic texts, following the horse’s Arabisation in the 9-10th century CE.