Iranian Zoroastrians are known to have been trading with India for centuries before the dates calculated for arrival of Parsis per Qissa-i Sanjan. Ruksana Nanji and Homi Dhalla while discussing archaeological evidence for 'The Landing of Zoroastrians at Sanjan', conclude that the most likely date for the migration at the start of the middle phase of their chronology, namely the early-to-mid-eighth century. Nevertheless, they express their general skepticism about the Qissa-i Sanjan account. Scholar Andre Wink has theorized that Zoroastrian immigrants to India, both before and after the Muslim conquest of Iran, were primarily merchants, since evidence suggests it was only some time after their arrival that religious experts and priests were sent for to join them. He argues that the competition over trade routes with Muslims may also have contributed to their immigration.