Astronomical tables—such as the Shahryar Tables—date to this period, and Sassanid observatories were later imitated by Muslim astronomers and astrologers of the Islamic period. In the mid-Sassanid era, an influx of knowledge came to Persia from the West in the form of views and traditions of Greece which, following the spread of Christianity, accompanied Syriac (the official language of Christians as well as the Iranian Nestorians). The Christian schools in Iran have produced great scientists such as Nersi, Farhad, and Marabai.