people think that when an army rolls in, they bring their own women or something.
Process of Arabisation was slow.
Rashidun when they conquered Egypt did not even bother imposing Arabic as they left the Copts to themselves.
Process of Arabisation really took off under the Ummayads who imposed Arabic as the official language of their empire.
Arabic became the lingua franca of the Islamic World. Everybody was communicating in Arabic.
Process of Arabisation is interesting because even under Non Arab Muslim rulers the process still continued under them.