[Ruling on Preferential Entitlement to Maḥājir Between Two Neighboring Villages]

Answer—and Allah is the Guardian of success and of guiding to the most upright path: People’s customs have long established that whoever precedes to what is permissible is most entitled to it, and that whoever has something in his hand of maḥājir, watercourses, or trees is more entitled to it. Thus have the customs of the people in our lands proceeded, generation after generation. Therefore we say: the tribe that has many maḥājir under its hand are the ones who are rooted and established in those lands, to the exclusion of the other tribe.
According to these customs, the tribe that does not have maḥājir under its hand has no right to demand from the tribe that does; for it has, by custom, no right in those maḥājir. One should not open up matters that people have come to agree upon, because that leads to strife, disputes, … etc.
This is when people are in a time of (political) interregnum. But if people are under a legitimate authority, then the Sultan of the Muslims—by virtue of his general guardianship—looks to what rectifies the affairs of the Muslims. He may confirm the maḥājir for their holders, or take from them what he wishes and place it where he wishes, according to what he sees to be in the public interest.
Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.2