The year of Salih's birth is not known.[1] He was one of at least two sons of a mawlā (Muslim convert or freedman) originally from Sijistan called Abd al-Rahman.[2] The latter had been taken captive in 650/51 by the troops of Rabi ibn Ziyad al-Harithi, an Arab commander dispatched to Sijistan by the governor of Basra, Abd Allah ibn Amir, who at the time was leading an expedition in Khurasan.[2] Together with his wife, Abd al-Rahman, whose original name is not known, was captured in the village of Nashrudh during one of Rabi's raids in the vicinity of Zaranj.[3] They were brought to the Arab garrison town and provincial center of Basra, where both were purchased by a certain Abla, a woman of the Banu Tamim, and then freed by her upon their conversion to Islam.[3]