A 9th-century Coin

Obverse: Sasanian-style bust right wearing winged crown; in margin: Muhammad is the messenger of God, from what the emir Talha ordered under the authority of ‘Abd Allah.” Reverse, in field: “There is no god except God alone, who has no associate.” [NB: all of the versions I could find of Sasanian-style Tahirid coins were from the 820s]

A 9th-century Coin

Obverse, in field: “al-Shukr, no god but God, unique, He has no associate, b. Ibrahim,” in margin: “in the name of God this dirham was struck in Madinat Herat year six and two hundred.” Reverse, in field: “Muhammad is the messenger of God, Dhu’l-Yaminayn”; “Muhammad is the messenger of God who sent him with guidance and the religion of truth that he might make it supreme over all other religions, even though the polytheists may detest it” (Q9:33). Dhu’l-Yaminayn, the “Ambidextrous,” was the nickname of Tahir b. Husayn, the founder of the Tahirids.

A 9th-century Poem

This poem was written by Di ‘bil b. ‘Ali, an opponent of the Tahirids.

Source, p. 17.

A 9th-century Description

Mutawakkil’s son ruled for only 6 months before he died and the grandson of Mu’tasim came to power. This snippet describes his rise to the Caliphate and the significance of the Tahirids under his rule. This passage is from an Arabic history written by Ya’qubi, who wrote both a history and a geography in the 9th century.

Source, pp. 1272-3.