Kazan Chronicle (Russian: Казанская летопись) or Story of the Tsardom of Kazan (Russian: История Казанского Царства) is a document written between 1560 and 1565 by a Muscovite chronicler. The chronicler introduces himself as a Russian who was held in captivity in Kazan for about 20 years until Ivan the Terrible sacked Kazan in 1552. In some sources his name is given as Ioann Glazaty (John the Big Eyes). While in captivity, the chronicler assumed Islam, which gave him substantial freedom to explore the local customs. The document deals with events from formation of Kazan Khanate in the first half of 15th century until its annexion in 1552. The authenticity of events, particularly events before the date when the chronicler came to Kazan, is doubtful. The chronicle contains numerous errors, a