Abu Shuja had lived in Baghdad during his youth with his father, Baha' al-Dawla.
Shortly before Baha' al-Dawla's death in 1012, he had named Abu Shuja as his successor.
Upon succeeding his father, he had taken the title Sultan al-Dawla wa 'Izz al-Milla ("Power of the Dynasty and Glory of the Community").
Traveling to his father's capital in Shiraz, he did seek for the traditional investiture by the Abbasid caliph, but instead had the required materials sent to him.
He had entrusted his oldest brothers Jalal al-Dawla and Qawam al-Dawla with the governorships of Iraq and Kerman, respectively.
He stayed in Persia for a long time; when he returned to Iraq three years later, he only went to Ahvaz to meet with his governor.
Sultan al-Dawla had again come to Iraq in 1018, in an attempt to maintain friendly terms with the neighboring Amirate of Mosul.
Qawam al-Dawla, taking advantage of his brother's presence in the west, had invaded Fars with the support of the Ghaznavids.
The attack had failed, but Qawam al-Dawla's marks the division of the Buyid state.
After repulsing Qawam al-Dawla's attack, Sultan al-Dawla had returned to Iraq in order to solidify his rule there.
The marchlands of the region, which had long resisted Buyid authority, were finally subjugated.
The Turkish mercenaries, however, have become discontented over the presence Sultan al-Dawla's Daylamite troops.
They therefore raise a brother of the amir, Musharrif al-Dawla, as their ruler in 1021.
After a long series of negotiations, Sultan al-Dawla recognizes his brother as "King of Iraq", in exchange for the latter's submission as a vassal.
Sultan al-Dawla, however, wantsto retain direct rule over the region, and he invades with his army.
His defeat by Musharrif al-Dawla's forces puts an end to this plan, and Iraq becomes fully independent.
The concept of the senior amir temporarily dies; each region of the Buyid state is now ruled independently of one another.
Musharrif al-Dawla hereafter will consider himself as Sultan al-Dawla's equal and assumes the title of "Shahanshah".
For the rest of his reign, he will be forced to placate the troops that had brought him to power.
