The collapse of the Persian Sassanid Empire in the 7th century CE caused the state religion to be switched from Zoroastrianism to Islam. Zoroastrianism slowly went from the religion of most in Iran, to a persecuted minority. For the survival of their faith and their lives, a large number of Zoroastrians chose to emigrate. According to the Qissa-i Sanjan, one group of those refugees landed in what is now Gujarat, India, where they were allowed greater freedom to observe their old customs and to preserve their faith. The descendants of those Zoroastrians, now known as the Parsis, would play a small but significant role in the development of India. Today there are around 70,000 Parsis in India. The Parsis, as Zoroastrians, still use a variant of the religious calendar instituted under the Sassanids. That calendar still marks the number of years since the accession of Yazdegerd III, just as it did in 632 CE.