Career
Prior to his appointment Thomas had served as a cleric in Mongol-ruled Turkestan. Thomas is known from the Mirabilia of Friar Jordanus, which describes him as bishop of "Semiscat". This place was positively identified as Samarkand during the nineteenth century.
Thomas, according to the Mirabilia, accompanied Jordanus on a journey to take the pall, an ecclesiastical vestment, to John de Cora, the newly appointed archbishop of Sultaniyah in Persia.
Thomas"s bishopric, along with that of Jordanus, fell within the province of this new metropolitan.