Beginning in the early 18th century, a schism befell the Zoroastrian communities of India nominally concerning the religious calendar. Though it had been noticed before, when an Iranian named Jāmāsp Hakīm Vilāyatī came to Gujarat from Iran bearing a response to religious enquiries, he found that there was a one month discrepancy between the Indian and the Iranian religious calendars and encouraged the Parsis to rectify their calendar with that of Iran. This rift, about the kabīsa or “intercalation,” split the community into two groups who became known as the Shahanshāhīs, those who maintained the Indian calendar and ceased to recognize the priestly authority of Iran, and the Qadīmīs, those who synchronized their calendar and continued to recognize the priestly authority of the Iranians. As a result, the centuries-old Rivāyat system in which Zoroastrian communities from India would send religious enquiries to the learned priests of Iran ceased to apply to the Shahanshāhīs. The calendar controversy dominated Parsi religious debate well into the 19th century in Bombay, when a number of treatises were published by rival priests. Though discourse about the kabīsa focused on the religious calendar, what was in effect at stake was the politics of memory. For Qadīmī priests like the famous Mullā Fīrūz, Iran was a locus memoriae, intrinsically connected with the events of Zoroastrian mytho-history. But for Shahanshāhī priests, the Iranian communities were increasingly seen as being in decline, and the mnemonic landscape of India itself began to grow in importance. In this paper, I will examine some aspects of this fascinating controversy, occurring at a crucial moment when the Parsis began to transition to British colonialism, using unpublished and published Persian and Gujarati sources from the late 18th and early 19th centuries.