There were 5 central boards existed under the umayyads:
1 Diwanu’l jund 2 Diwanu’l-kharaj 3 Diwanu’r-Rasa’il 4 Diwanu’l-Khatam 5 Diwanu’l-barid
These were continued under the early “ Abbasids, and many more added to them. In the end of the first century of the Abbasid rule, the following Boards seem to have been established:
6 Diwanu’l-azimmah( the Audit and account board) 7 Diwanu-Nazir fil-mazalim (the board of investigation of Grievances). 8 Diwanu’n-nafaqat (the board of Expenditure) 9 Diwanu’s-sawafi (the board of Crownlands) 10 Diwanu-Diya (the board of estates) 11 Diwanu’s-sirr (the board of Secrecy) 12 Diwanu’l-Ard (the board of Military inspection) 13 Diwanuttawqi (the board of request)
1 Diwanu’l jund This diwan was responsible for the recruitment and pay of the troops. Actually, the Caliph or Wazir looked after these matters which were among the most important in the state.
2 Diwanu’l-kharaj This diwan not only kept the account of the taxes collected, but also maintained the records of the expenditure.in this way it bocome the central finance board.
Von Kremer, Ameer Ali, Mez and Levy write that this Board was displaced by Diwanul Tawql, Al-Jahahiyari mentions Diwanu’l Khatam under several of the ‘Abbasid rulers. According to him, this Boardwas in existence even under al-Amin (09-814 A.D.) Mez writes that Diwanut-Tawqi’ was presided over by Ja’far, the great Wazir of ar-Rashid (786-809 A>D) Ja’far (ex.803 A>D) presided over Diwanu’n-Nazri fi’l-Mazalim, and the orders were known as the tawqi’at. Thus we see that Diwaru’l-Khatam continued at least for a decade even after the establishment of Diwanu’t-Tawqi.
There was a central office at Baghdad which received mails and reports from the whole of the Empire and sorted and disturbed them to the various departments.
Some writers have wrongly called it Diwanuz-Zimam. This Diwan, founded by al-Mahdi (158-168) A.H., was called Diwanl-Azimmah at the Centre and Diwanz-Zimam in the provinces. This Board concerned itself with audit and accounts and was an effective means of improving the administration. All provincial audits and accounts officers were under the jurisdiction.
7 Diwanu-Nazir fil-mazalim (the board of investigation of Grievances).
This Board was concerned with the requirements of the court. It dealt with the salaries of court officials, provisions (bread, meat, sweets, eggs, fruits, fuel,etc), constructions and repairs of the royal buildings, and care of the stables (horses, mules, camels, other animals, and their fodder) and met all contingent expenses connected with the requirements of the court.
9 Diwanu’s-Sawafi and Diwanud-Diya’
As-Sawafi means crown-land and ad-Diva’ means estates. Both these Boards are mentioned by al-jahahiyari. Buyyt the passatge dealing with ad-Diya” reads” And (al-Mansur) placed Said, his mawla, in charge of his estates.” Therefore, it appears that the crown-lands were under Diwandu’s Sawafi and the personal estates of the Caliph under Diwanud-Diya.
This Board is mentioned in two places by al-Jahshiyari, that is, under al-Mansur and under ar-Rashid’. In both the place it is reported to be under the same officer who was incharge of Diwanu’r Rasa’il. Possibly it was a section or department of Diwanu’r Rasa’il.
This Board is also mentioned by al-Jahshiyar. It concerned itself with the inspection of military equipment, etc. The arsenals were under a special officer called the Mushrifu’s Sanaati bil-Makhzan. Whether this Board was a part of Diwanu’l-Jund or an independent one is not clear.
This Diwan was established which drew up formal documents baased on these short notes, entered them into a register, and sent them on the concerned persons. This Diwan seems to have taken up the work of Diwanu’l-Khatam as well. But Diwanu’l-Khatam is mentioned under the early ‘Abbasids including the reign of al-Amin.
It was in the days of al-Mahdi that the institution of the chief judge (Qadiul-Qadat) came into existence. While at Medina the Prophet himself acted as the chief judge, and had also appointed Qadis for the various provinces of Arabic. Later, the Caliph appointed Qazi who work independent and had neither subordinate under them nor were they under any superior Qadis. Al-Mahdi appointed Abu Yousuf, the most illustrious student of Imam Abu Hanifah, as the Qazi of Qadis. So far, the provincial Qadis were appointed by the Governors of the respective, provinces or directly by the Caliph.
The police was called ash-Shurtah and the poplice officer Shibu’sh-Shurtah by Ali who was responsible for instituting the office. When the ‘Abbasids came to power, the police officer once more became Sahibu’sh-Shurtah. The chief police officer at Baghdad ranked almost as a Governor, and under the later’Abbasids presided over a Diwan and held the rank of a minister. Under the early ‘Abbasids he was the chief of the bodyguard of the Caliph and executed death sentences.
Among the pre-Islamic Arabs it was customary to lead the prisoners alaong the streets in chains.
Under the early ‘Abbasids, the old practice of leading the prisoners along the streets seems to have been revived. Abu Yusuf vehemently criticizing the practice writes. “It is incumbent that every non-Muslim should be fed and well treated till his case is decided. Then what about a Muslaim, who has committed a mistake or a crim? Is he to be left to die of starvation because fate or ignorance has forced him to become what he is?”.... “Do away with leading them in chains for people to give alms to them; for it is a great wrong that Muslims, who have committed some crimes or mistakes. (God having ordained that they should be imprisoned and led outin chains to be bestowed with alms.
All the four great schools of Muslim jurisprudence, which are still called by the names of their founders, Abu Hanifah, Malik bin Anas, Asha-Shafii and Ahmad bin Hanbal, flourished under the early ‘Abbasids. ‘Abdullah bin al-Abbas cousin of the Holy Prohphet, was the real founder of Quranic exegensis (at-tafsir). Thus during the early period of the ‘Abbasid rule, the meanings of the verses of the Quran were made more or less definite and the great mass of the sayintgs of the Prophet and reports about his doings collected and arranged. Further, Muslim law was codified and regulations regarding the various religious duties and ceremonies fixed by the four great schools of Muslims law and jurisprudence (al-fiqh). Thus a few marked steps were taken in the direction of making a hitherto elastic and dynamic creed definite and statistic. For the first time in Islam organized religious persecution and inquisition by the state began under the ‘Abbasids. Al-Mahdi established a department of the State to hunt down the heretics and appointed a minister to be in charge of it. He was called Sahibu’z-Zanadiqah. Arrangements for the conduct of prayers throughout the Empre were made as during the previous periods. Thousands of mosques were built. Baghdad alone had 27,000 of them, and the Hajj ceremony was organized by the government as usual. On the whole, there was more of formal religious observances under the ‘Abbasids than before. By gthe end of Umayyad period the conflict between the spread of Islam and the financial interests of the State disappeared. All land-owners had to pay al-kharaj in the kharaj area and al-Jizya was removed from all Muslims. Thus under the early “Abbasids the entire Muslim Empire was Islamized by removing all impediments in the way of new converts and by offering them equal status with the old Muslims both in theory and in practice.