The first change made by the Abbasids under Al-Mansur was to move the empire's capital from Damascus to a newly founded city.
Established on the Tigris River in 762, Baghdad was closer to the Persian mawali support base of the Abbasids, and this move addressed their demand for less Arab dominance in the empire.
A new position, that of the vizier, was also established to delegate central authority, and even greater authority was delegated to local emirs.
Caliph al-Mansur centralised the judicial administration, and later, Harun al-Rashid established the institution of Chief Qadi to oversee it.

This resulted in a more ceremonial role for many Abbasid caliphs relative to their time under the Umayyads; the viziers began to exert greater influence, and the role of the old Arab aristocracy was slowly replaced by a Persian bureaucracy.
During Al-Mansur's time, control of Al-Andalus was lost, and the Shia revolted and were defeated a year later at the Battle of Bakhamra.

The Abbasids had depended heavily on the support of Persians in their overthrow of the Umayyads.
Abu al-'Abbas' successor Al-Mansur welcomed non-Arab Muslims to his court.
While this helped integrate Arab and Persian cultures, it alienated many of their Arab supporters, particularly the Khorasanian Arabs who had supported them in their battles against the Umayyads.
This fissure in support led to immediate problems.
The Umayyads, while out of power, were not destroyed; the only surviving member of the Umayyad royal family ultimately made his way to Spain where he established himself as an independent Emir (Abd ar-Rahman I, 756).
In 929, Abd ar-Rahman III assumed the title of Caliph, establishing Al Andalus from Córdoba as a rival to Baghdad as the legitimate capital of the Islamic Empire.

In the year 755, during the early stages of the Abbasid Caliphate, the people of current day Somalia around Mogadishu showed great loyalty to the newly created administration.
It is reported that Yahya ibn Umar al Anzi the messenger of the second caliph of the Abbasids Abu Ja'far al-Mansur that the Sultan of Mogadishu and his people swore allegiance to the Caliphate and paid taxes regularly.

However, in the year 804 (189 AH), the people of Mogadishu and the Swahili coast to Kilwa rebelled against the Abbasid rule and the administration of Harun al-Rashid.
Additionally, they refused to pay tax.
Harun al-Rashid sent a successful punitive mission to the region to reassert Abbasid control and sovereignty.
Despite this, the Sultanate of Mogadishu remained in constant rebellion.

In 829 Al Ma'mun the 7th Caliph of the Abbasids sent an army of 50,000 men to crush the secessionist enclaves and add them back to the Caliphate.

In 756, the Abbasid Caliph Al-Mansur sent over 4,000 Arab mercenaries to assist the Chinese Tang dynasty in the An Shi Rebellion against An Lushan.
The Abbasids, or "Black Flags" as they were commonly called, were known in Tang dynasty chronicles as the hēiyī Dàshí, "The Black-robed Tazi" (黑衣大食) ("Tazi" being a borrowing from Persian Tāzī, the word for "Arab").
 Al-Rashid sent embassies to the Chinese Tang dynasty and established good relations with them.
After the war, these embassies remained in China with Caliph Harun al-Rashid establishing an alliance with China.
Several embassies from the Abbasid Caliphs to the Chinese court have been recorded in the T'ang Annals, the most important of these being those of Abul Abbas al-Saffah, the first Abbasid caliph; his successor Abu Jafar; and Harun al-Rashid.
The first change made by the Abbasids under Al-Mansur was to move the empire's capital from Damascus to a newly founded city. Established on the Tigris River in 762, Baghdad was closer to the Persian mawali support base of the Abbasids, and this move addressed their demand for less Arab dominance in the empire. A new position, that of the vizier, was also established to delegate central authority, and even greater authority was delegated to local emirs. Caliph al-Mansur centralised the judicial administration, and later, Harun al-Rashid established the institution of Chief Qadi to oversee it.
This resulted in a more ceremonial role for many Abbasid caliphs relative to their time under the Umayyads; the viziers began to exert greater influence, and the role of the old Arab aristocracy was slowly replaced by a Persian bureaucracy. During Al-Mansur's time, control of Al-Andalus was lost, and the Shia revolted and were defeated a year later at the Battle of Bakhamra.
The Abbasids had depended heavily on the support of Persians in their overthrow of the Umayyads. Abu al-'Abbas' successor Al-Mansur welcomed non-Arab Muslims to his court. While this helped integrate Arab and Persian cultures, it alienated many of their Arab supporters, particularly the Khorasanian Arabs who had supported them in their battles against the Umayyads. This fissure in support led to immediate problems. The Umayyads, while out of power, were not destroyed; the only surviving member of the Umayyad royal family ultimately made his way to Spain where he established himself as an independent Emir (Abd ar-Rahman I, 756). In 929, Abd ar-Rahman III assumed the title of Caliph, establishing Al Andalus from Córdoba as a rival to Baghdad as the legitimate capital of the Islamic Empire.
In the year 755, during the early stages of the Abbasid Caliphate, the people of current day Somalia around Mogadishu showed great loyalty to the newly created administration. It is reported that Yahya ibn Umar al Anzi the messenger of the second caliph of the Abbasids Abu Ja'far al-Mansur that the Sultan of Mogadishu and his people swore allegiance to the Caliphate and paid taxes regularly.
However, in the year 804 (189 AH), the people of Mogadishu and the Swahili coast to Kilwa rebelled against the Abbasid rule and the administration of Harun al-Rashid. Additionally, they refused to pay tax. Harun al-Rashid sent a successful punitive mission to the region to reassert Abbasid control and sovereignty. Despite this, the Sultanate of Mogadishu remained in constant rebellion.
In 829 Al Ma'mun the 7th Caliph of the Abbasids sent an army of 50,000 men to crush the secessionist enclaves and add them back to the Caliphate.
In 756, the Abbasid Caliph Al-Mansur sent over 4,000 Arab mercenaries to assist the Chinese Tang dynasty in the An Shi Rebellion against An Lushan. The Abbasids, or "Black Flags" as they were commonly called, were known in Tang dynasty chronicles as the hēiyī Dàshí, "The Black-robed Tazi" (黑衣大食) ("Tazi" being a borrowing from Persian Tāzī, the word for "Arab").  Al-Rashid sent embassies to the Chinese Tang dynasty and established good relations with them. After the war, these embassies remained in China with Caliph Harun al-Rashid establishing an alliance with China. Several embassies from the Abbasid Caliphs to the Chinese court have been recorded in the T'ang Annals, the most important of these being those of Abul Abbas al-Saffah, the first Abbasid caliph; his successor Abu Jafar; and Harun al-Rashid.
Abbasid Caliphate