10. How lineages become confused.
It is clear that a person of a certain descent may become attached to people of another descent, either because he feels well-disposed toward them, or because there exists an (old) alliance or client(-master) relationship, or yet because he had to flee from his own people by reason of some crime he committed. Such a person comes to be known as having the same descent as those (to whom he has attached himself) and is counted one of them with respect to the things that result from (common descent), such as affection, the rights and obligations concerning talion and blood money, and so on. When the things which result from (common) descent are there, it is as if (common descent) itself were there, because the only meaning of belonging to one or another group is that one is subject to its laws and conditions, as if one had come into close contact with it. In the course of time, the original descent is almost forgotten. Those who knew about it have passed away, and it is no longer known to most people. Family lines in this manner continually changed from one tribal group to another, and some people developed close contact with others (of a different descent). This happened both in pre-Islamic and in Islamic times, and between both Arabs and non-Arabs. If one studies the different opinions concerning the pedigree of the family of al-Mundhir 56 and others, the matter will become somewhat clearer.
The affair of the Bajilah and 'Arfajah b. Harthamah is an(other) illustration. When 'Umar appointed 'Arfajah their governor, (the Bajilah) asked ('Umar) to withdraw him, saying that he was a nazif 57 among them, that is, one who had come to them from outside and attached himself to them. They asked that he appoint Jarir (instead). 'Umar asked 'Arfajah about this, and he replied: "They are right, O Commander of the Faithful. I am from the Azd. I shed blood among my people, and joined (the Bajilah)." 58 This shows how 'Arfajah had come to mix with the Bajilah, had become of their skin, and was known as one having the same descent as they, to the extent that he could eventually become a candidate for leadership over them, (and would have) had someone not remembered the genealogical ramifications. Had they overlooked it and had (still) more time elapsed, (his foreign origin) would have been forgotten, and he would have been considered one of them in every respect.
This should be understood and pondered as one of God's ways with His creatures. Similar things occur frequently in our own times, and have always been frequent in former times.59