Tachkastan
The phrase Tajh of Mehmet refers to the Messianic Mithraists of Tachkastan who had been united to the proto-Karaites as Hagarim by Mehmet Ismaili.
The word Mehmet is the Persian form of Mohmad, the Arabian Gnostic name for Jesus Patibilis, which derives from the Hebrew word Mahmad used to refer to the Temple as part of the Bridegroom-Lord mentioned in Jewish writings.
The ethnonym "Tajh" was pronounced approximately as "Taye" by Afroasiatics and approximately as "Tazik" by Indoeuropeans and Tashih in Chinese sources. Soghdian Manichean sources call them Tazigan and consider them to have been a related Gnostic group. Those that later arrived in Romania were called Tzigane.
The first known Tajh of Mehmet was named by Sebeos as Mehmet Ismaili who may have been the historical 7th century figure behind the Islamic legends of Iyas ibn Qabisa and Muhammad ibn Abdullah.
