The inscription is from the Qu'ran, sura al-fatiha (i) and dated rajab 666/March-April, 1268.
A larger opaque turquoise glazed mihrab is in the Metropolitan Museum of Art (Carboni, Stefano and Masuya, Tomoko: Persian Tiles, New York, 1993, no.30, p.35). Dated 712/1312-13, nearly a century later than the present example, it demonstrates, as also noted by Venetia Porter (Islamic Tiles, London, 1995, p.11), how conservative some of the designs remained within Iran over long periods of time.