Question: Under which dynasty did this Persian general serve who used the Black Standard in his uprising leading to the Abbasid Revolution in 747?
Context: The Abbasid Revolution refers to the overthrow of the Umayyad Caliphate (661–750 CE), the second of the four major Caliphates in early Islamic history, by the third, the Abbasid Caliphate (750–1258 CE).  Coming to power three decades after the death of the Muslim prophet Muhammad and immediately after the Rashidun Caliphate, the Umayyads were a feudal Arab empire ruling over a population which was overwhelmingly non-Arab as well as primarily non-Muslim.  Non-Arabs were treated as second class citizens regardless of whether or not they converted to Islam, and this discontent cutting across faiths and ethnicities ultimately led to the Umayyads' overthrow.  The Abbasid family claimed to have descended from al-Abbas, an uncle of the Prophet. Khazim ibn Khuzayma al-Tamimi (  749–768 ) was a Khurasani Arab military leader.  One of the early supporters of the Abbasid "da'wa" in Khurasan, he played a major role in the Abbasid Revolution against the Umayyads, and then spent the next two decades suppressing revolts across the Caliphate.  As one of the main figures of the "Khurasaniyya", the main power base of the Abbasid regime, he cemented his family in a position of power and influence: his sons would play an important role in the affairs of the Caliphate over the next decades. The abnāʾ al-dawla (meaning "sons of the regime/dynasty"), often simply " the "Abnāʾ"", is a term for the Khurasani Arabs who had participated in the Abbasid Revolution of 749–750 and their descendants, who settled in Baghdad and Iraq.  They became the ruling elite of the Abbasid Caliphate and formed the mainstay of the caliphal army.  However, the term appears rarely in the sources until the time of the Fourth Fitna civil war in the 810s, when it is applied to the Khurasanis of Baghdad, who overwhelmingly supported Caliph al-Amin against his brother al-Ma'mun.  The terms "ahl Khurāsān" ("people of Khurasan") and "abnāʾ ahl Khurāsān" ("sons of the people of Khurasan") are more frequently used for the Khurasanis who formed the mainstay of the Abbasid regime in general.  Following al-Ma'mun's victory in the civil war, the "abnāʾ al-dawla" were largely replaced by the latter's Persian followers, and under his successor al-Mu'tasim, the rise of the Turkish slave-soldiers to power began. Abu Muslim Abd al-Rahman ibn Muslim al-Khorasani or al-Khurasani (Arabic: أبو مسلم عبد الرحمن بن مسلم الخراساني‎ ‎ born 718-19 or 723-27, died in 755), born Vehzādān Pūr-i Vandād Hormoz (Persian: وهزادان پور ونداد هرمزد‎ ‎ ), was a Persian general in service of the Abbasid dynasty, who led the Abbasid Revolution that toppled the Umayyad dynasty. The Siege of Wasit involved the army of the Abbasid Revolution under al-Hasan ibn Qahtaba and the future Caliph al-Mansur, and the Umayyad garrison of Wasit under the last Umayyad governor of Iraq, Yazid ibn Umar ibn Hubayra.  Yazid had been forced to abandon Kufa due to a rebellion by Abbasid sympathizers, and fled to Wasit, where he was besieged for 11 months, from August/September 749 to his surrender in June/July 750.  The siege was marked by constant sallies and attacks, but as it progressed, the Umayyad garrison's morale collapsed and the internal divisions among the Qays and Yaman tribes began to manifest themselves.  After news of the defeat of the Umayyad Caliph Marwan II at the Battle of the Zab and the Abbasid conquest of Syria arrived at Wasit, defections began.  Yazid nevertheless held out for a few more months, until he received a pardon for himself and his followers from the Abbasid Caliph al-Saffah.  Nevertheless, Yazid and his senior officers were executed soon after on al-Saffah's orders. The Black Banner or Black Standard (Arabic: راية السوداء‎ ‎ "rāyat as-sawdāʾ", also known as راية العقاب "rāyat al-ʿuqāb" "banner of the eagle" or simply as "ar-rāya " "the banner") is one of the flags flown by Muhammad in Islamic tradition.  It was historically used by Abu Muslim in his uprising leading to the Abbasid Revolution in 747 and is therefore associated with the Abbasid Caliphate in particular.  It is also a symbol in Islamic eschatology (heralding the advent of the Mahdi). The Third Fitna (Arabic: الفتنة الثاﻟﺜـة‎ ‎ ; "al-Fitna al-thālitha"), was a series of civil wars and uprisings against the Umayyad Caliphate beginning with the overthrow of Caliph al-Walid II in 744 and ending with the victory of Marwan II over the various rebels and rivals for the caliphate in 747.  However, Umayyad authority under Marwan II was never fully restored, and the civil war flowed into the Abbasid Revolution (746–750) which culminated in the overthrow of the Umayyads and the establishment of the Abbasid Caliphate in 749/50.  Thus a clear chronological delimitation of this conflict is not possible. The Tahirid dynasty (Persian: طاهریان‎ ‎ , "Tâhereyân") was a dynasty, of Persian dihqan origin, that governed the Abbasid province of Khorasan from 821 to 873 and the city of Baghdad from 820 until 891.  The dynasty was founded by Tahir ibn Husayn, a leading general in the service of the Abbasid caliph al-Ma'mun.  Their capital in Khorasan was initially located at Merv but was later moved to Nishapur.  The Tahirids enjoyed a high degree of autonomy in their governance of Khorasan, but they remained subject to the Abbasid caliphate and were not independent rulers. Abdallah ibn al-Abbas (ca. 712 – 764 CE) was a member of the Abbasid dynasty, who played a leading role in its rise to power during the Abbasid Revolution.  As governor of Syria, he consolidated Abbasid control over the province, eliminating the remnants of the Umayyad dynasty and suppressing pro-Umayyad uprisings.  After the death of his nephew and first Abbasid Caliph, al-Saffah, in 754, he launched a bid for the caliphal title against al-Saffah's brother, al-Mansur, but was defeated and imprisoned.  He was killed in 764. The Alid revolt of 762–763 or Revolt of Muhammad the Pure Soul was an uprising by the Hasanid branch of the Alids against the newly established Abbasid Caliphate.  The Hasanids, led by the brothers Muhammad (called "the Pure Soul") and Ibrahim, rejected the legitimacy of the Abbasid family's claim to power.  Reacting to mounting persecution by the Abbasid regime, in 762 they launched a rebellion, with Muhammad rising in revolt at Medina in September and Ibrahim following in Basra in November.  The lack of co-ordination and organization, as well as the lukewarm support of their followers, allowed the Abbasids under Caliph al-Mansur to react swiftly.  The Caliph contained Muhammad's rebellion in the Hejaz and crushed it only two weeks after Ibrahim's uprising, before turning his forces against the latter.  Ibrahim's rebellion had achieved some initial successes in southern Iraq, but his camp was riven by dissent among rival Shi'a groups as to the prosecution of the war and future political objectives.  In the end, Ibrahim's army was decisively defeated at Bakhamra in January 763, with Ibrahim dying of his wounds shortly after.  The failure of the rebellion did not mark the end of Alid unrest, but it consolidated the power of the Abbasid dynasty.
Answer: Abbasid dynasty