•Signs
of decline were present during the reign of Caliph al-Mahdi
(775-785).
•He
failed to reconcile moderate Shi'i to Abbasid rule.
•Al-Mahdi
abandoned the frugal ways of his predecessor and surrounded his court
with luxury.
•He
failed to establish a succession system resolving disputes among
his many sons, leaving a lasting problem to future
rulers.