Family and early career
Ahmad was the son of Buya, a Daylamite fisherman from Lahijan, who had left his Zoroastrian faith and converted to Islam. Ahmad had two older brothers named 'Ali and Hasan, and a sister named Kama.
In around 928, Ahmad's brother Ali joined the services of Makan ibn Kaki, who was the Samanid governor of Ray. 'Ali then managed to gain military positions for Ahmad and another their other brother Hasan. At the time, Ahmad was about thirteen years old. When Makan attacked his Samanid overlords and was subsequently defeated by the Ziyarid prince Mardavij, the brothers transferred their allegiance to the latter. In the following years, 'Ali repudiated his subservience to Mardavij and, after some time, managed to create an empire in Fars, where Ahmad distinguished himself in battle.
In 935 or 936, 'Ali sent Ahmad to Kerman with the task of conquering that province from the Banu Ilyas. Ahmad overran much of Kerman, but encountered resistance from the Baluchis and Arab Qafs, receiving a wound to the head and losing a hand and several fingers on the other. Direct Buyid control over Kerman was not established, resulting in 'Ali's recall of Ahmad. The latter was then sent to Istakhr to await further orders.
Ahmad's next opportunity to expand the possessions of the Buyids came when the Baridis requested help from 'Ali. The Baridis, who ruled in Khuzestan, were nominally subordinate to the Abbasid Caliphate, but were attempting to establish their independence. Ahmad was sent by 'Ali to the area; he succeeded in uprooting the authority of the Baridis and taking control of that province.