>>18480
From the end of the Ridda wars to the halt of Abbasid expansion, around 800, although I do want to get into some later battles from the 10th century onwards. One of the things I find odd about the early Muslim expansion is that Eastern Arabia was actually part of the Sassanid Empire, but after the governor converted to Islam, it was basically treated as part of Muhammad's Caliphate, and while all of central Arabia was under Muslim control after the Ridda wars, it basically fell into anarchy for around a thousand years, up until the Diriyah Emirate. Other odd scenarios are for example, the Arab-Khazar wars, since Marwan ibn Muhammad technically won against the Khazars, but never really annexed it, and just went back to Damascus.
https://en.wikipedia.org/wiki/Arab%E2%80%93Khazar_wars