إِذْ أَحَلَّ الْعَلْيَاءَ قُبَّةَ مَيْسُونَ فَأَدْنَى دِيَارِهَا الْعَوْصَاءُ
Meaning: When Maysūn’s tent was set up at al-ʿAlyāʾ, al-ʿAwṣāʾ was the nearest of her encampments.
Here aḥalla means to establish or settle someone at a place; qubbah is a prominent tent. Al-ʿAlyāʾ and al-ʿAwṣāʾ are place names, while Maysūn is the woman associated with the encampment.
The concrete location follows the general boasting for a reason: it sets a scene for the gathering of forces in the next verse. The poetry moves from a broad claim into a remembered episode.