The opening builds the scene in a deliberate sequence.
1. لَمَّا اقْتَعَدْتُ... — Setting out into estrangement.
2. وَأَنَأَتْنِي... — Poverty and separation from companions.
3. طَوَّحَتْ بِي... — Being driven away by circumstances.
4. إِلَى صَنْعَاءَ الْيَمَنِ — Naming the destination.
In a few clauses, the author establishes background, emotion, driving force, and place. Understanding this structure makes the difficult diction easier to follow.