In his 2020 monograph, Andrew Harris portrays an inefficient imperial court in Constantinople. To offset weak defence on its Syria-Arabia frontier, the empire had for centuries "managed" the feuding Arab tribes by sponsoring the Christian Ghassanids and various compliant non-Christian Arabs. Held in check by the Ghassanids was the Sasanian'sLakhmid vassal-state. While Constantinople made it worth their while, the Ghassanids would remain loyal. By 630, Constantinople had ceased making the payments. There followed some defection to the Lakhmids. It seems some instalments may have resumed within six years, because the empire was able to draw on Ghassanid allies for the Battle of the Yarmuk. Constantinople's faltering strategy was symptomatic of internal malaise, fruit of religious sectarianism, factions jostling for the imperial succession, profligate finances, and territory again slipping away after the Byzantine–Sasanian War of 602–628. https://apps.dtic.mil/sti/trecms/pdf/AD1159100.pdf