The indigenous Arabian sky is organised around rain. The anwa system divides the year by the heliacal settings of twenty-eight star groups, the manazil al-qamar or lunar mansions, each setting in the west at dawn while its opposite rises, and each associated with an expected weather condition and a period of roughly thirteen days.
The naw itself is that setting, and the rain was said to come with it. Islam had a difficulty with this, since attributing rain to a star is close to attributing it to something other than God, and there is a well known hadith addressing the point directly: to say we have been given rain by such and such a star is one thing, and to say we have been given rain by the mercy of God is another. The system survived as an agricultural almanac with the theology adjusted.
The twenty-eight mansions are the same institution as the Indian nakshatras and the Chinese xiu, and the relationship between the three is a long-running question in the history of astronomy that has not been settled.
Banat Nash belongs to the same indigenous layer as the anwa rather than to the translated Greek layer, and the two coexisted in Arabic writing for centuries. Al-Sufi's Book of the Fixed Stars gives both, figure by figure, which is why so much of the older nomenclature survives at all.