The principal appellations for God/god in Middle Persian and Parthian were yazd and bay. In Modern Persian, however, they vanished altogether and were replaced by the term xodā, which in its Middle Persian and Parthian forms, that is xwadāy/xwadāw, belonged to a strictly political discourse with the meaning of "lord."The rare attestations of xwadāy in the meaning of "God/god" in the Middle Persian scriptures of the Zoroastrians (Pahlavi literature), written in the 9th and 10th centuries C. E., were probably influenced by the meaning of xodā in Modern Persian, which retroactively affected the Pahlavi literature by the intermediary of Zoroastrian priests and compilers, for whom the term xodā in the meaning of "God" was as familiar as were the terms yazd and bay within the Zoroastrian theological discourse. The discarding of the terms yazd and bay in Modern Persian and their replacement by the word xodā was the work of Zoroastrian converts who had recourse to a term, that could refer to God without reflecting the spiritual word of Zoroastrianism as did yazd and bay and could hence consummate the break with their Zoroastrian past.