وَقَدْ عَلِمَ الْقَبَائِلُ مِنْ مَعَدٍّ إِذَا قُبَبٌ بِأَبْطَحِهَا بُنِينَا
The tribes of Maʿadd have known us when our dome-shaped tents were pitched upon the plains.
Maʿadd is an ancestral designation linked with Arab tribal groups. Qubab here means large dome-like tents. The passive buninā describes their erection, not necessarily masonry buildings.
The clause with idhā specifies a scene in which the tribe’s presence is recognizable: encampments stand prominently across the plain. The physical size of the camp becomes an emblem of social influence.