Ya'qub ibn al-Layth Saffar (Persian: یعقوب لیث صفاری; 25 October 840 – 5 June 879),[1] was a coppersmith and the founder of the Saffarid dynasty of Sistan, with its capital at Zaranj (a city now in south-western Afghanistan).

Ya'qub was born in 840, of eastern Iranian origin,[4] in a small town called Karnin (Qarnin), which was located east of Zaranj and west of Bost (Lashkargah), in what is now Afghanistan.

Clifford Edmund Bosworth explains that several Sunni sources were invariably hostile to Ya'qub because of the disrespect he showed toward the Abbasid caliph.

[6] "Some sources accused Ya'qub of being a Khariji, Ibn Khallikan labeled him a Christian, and Nizam al-Mulk claimed that he converted to Ismailism".

In 864, "Yaʿqub led an expedition to Bost against his former master Salih, and then into Rukkaj and Zamindāvar against the local ruler there, the Zunbil, killing him and securing an immense booty.

He later moved against the Kharijites in northern Sistan, winning a decisive victory and killing their leader Ammar ibn Yaser in 865.

[11] Ya'qub claimed the inheritance of the kings of Persia and sought "to revive their glory," and thus in 867 he sent a poem written by himself to the Abbasid caliph Al-Mu'tazz.

[a] His army would later march to Ghazna, Kabul, and Bamyan, conquering these territories from the Hindu Shahi, and appointing Muslim governors.

In 873, Ya'qub ousted the Tahirids from their own capital of Nishapur,[15] and captured its ruler Muhammad ibn Tahir, which led to conflicts with the Abbasid caliphate.

Sources disagree on what happened next, but Ya'qub was eventually dissuaded from continuing his expedition, and he turned back toward Sistan.

His withdrawal is described as having been caused either by the governor Muhammad ibn Wasil's submission to him, or by the arrival of emissaries sent by the caliphal government to convince him to abandon his westward advance.

Ya'qub ibn al-Layth once again set out for Fars, this time, invading it and advancing to Estakhr, seizing Muhammad's treasuries there.

[21][22][23] In 876, the Abbasid representative Al-Muwaffaq offered Ya'qub governorship of Khurasan, Tabaristan, Fars, Gurgan, and Ray, and to appoint him as head of security in Baghdad.

[24][25][26][b] Ya'qub, sensing that the offer was made due to the weakness of the caliph, rejected it and wrote back that he would be advancing to the capital.

Seeing that an agreement with the Saffarid was impossible, the Abbasid caliph al-Mu'tamid decided upon war and pronounced a formal curse upon Ya'qub.

Ya'qub traveled through Khuzistan, during which he gained the defection of a former general of the caliph's, Abi'l-Saj Devdad, and entered Iraq.

[43][48][38][47][49] The caliph had apparently flooded the lands behind the Saffarids before the battle, and this made a retreat difficult; many men drowned attempting to escape the Abbasid army.

Several political prisoners that Ya'qub had brought with him, such as the Tahirid Muhammad bin Tahir, also fell into Abbasid hands and were freed.

[3] Several poets, like Abu Ishaq Ibrahim ibn Mamshadh, fabricated Ya'qub's genealogy, tracing it back to the legendary Iranian king Jamshid.