«فَمَا دَخَلْتُ مَدِينَةً وَلَا وَلَجْتُ عَرِينَةً إِلَّا وَامْتَزَجْتُ بِحَاكِمِهَا»
I entered no city or settlement without establishing ties with its ruler.
Mā dakhaltu ... wa-lā walajtu ... illā is a negative-exceptive construction. The clause introduced by wa-mtazajtu bi-ḥākimihā describes the accompanying practice: whenever the narrator entered a place, he established a relationship with its ruler.
The syntax presents a habit across different cities. Reading the exception as a separate unrelated event would miss how tightly the two actions are linked.