The House of al-Fadl ibn Mahan at Sindan

Al-Baladhuri reports that al-Fadl ibn Mahan, a client of the Banu Sama, conquered Sindan and prevailed over it, and he invoked al-Ma'mun in a congregational mosque that he built there. ¹

Al-Fadl sent an elephant and his scribe to al-Ma'mun. When he died his son Muhammad took his place, and set out with seventy warships to the Indian coast, where he killed a great number. He returned to Sindan, where a brother of his called Mahan had prevailed, so he wrote to al-Mu'tasim and sent him a great quantity of teak. ¹

Al-Baladhuri says that the Indians turned against Mahan, killed him and crucified him, then prevailed over Sindan, and left its mosque for the Muslims to gather in and pray for the caliph. ¹

No dates are given in this text. An additional source is needed.