The Tahirid dynasty (Persian: سلسله طاهریان‎) was a Persian dynasty 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 later moved to Nishapur. The Tahirids enjoyed a high degree of autonomy in their governance of Khorasan, although they remained subject to the Abbasid caliphate and were not independent rulers.

The founder of the Tahirid dynasty was Tahir ibn Husayn, a general who had played a major role in the civil war between the rival caliphs al-Amin and al-Ma'mun. He and his ancestors had previously been awarded minor governorships in eastern Khorasan for their service to the Abbasids. In 821, Tahir was made governor of Khorasan, but he died soon afterwards. The caliph then appointed Tahir's son, Talha, whose governorship lasted from 822–828. Tahir's other son, Abdullah, was instated as the wali of Egypt and the Arabian Peninsula, and when Talha died in 828 he was given the governorship of Khorasan. Abdullah is considered one of the greatest of the Tahirid rulers for the dynasty witnessed in his reign flourishing agriculture in his native land of Khorasan, popularity among the populations of the eastern lands of the Abbasid caliphate and extending influence due to his experience with the western parts of caliphate.