The ''Book of Dede Korkut'' consists of two manuscripts copied in the 16th century, and was not written earlier than the 15th century. It is a collection of 12 stories reflecting the oral tradition of Oghuz nomads. The 16th-century poet, Muhammed Fuzuli produced his timeless philosophical and lyrical ''Qazals'' in Arabic, Persian, and Azerbaijani. Benefiting immensely from the fine literary traditions of his environment, and building upon the legacy of his predecessors, Fuzuli was destined to become the leading literary figure of his society. His major works include ''The Divan of Ghazals'' and ''The Qasidas''. In the same century, Azerbaijani literature further flourished with the development of Ashik () poetic genre of bards. During the same period, under the pen-name of Khatāī ( for ''sinner'') Shah Ismail I wrote about 1400 verses in Azerbaijani, which were later published as his ''Divan''. A unique literary style known as ''qoshma'' ( for ''improvisation'') was introduced in this period, and developed by Shah Ismail and later by his son and successor, Shah Tahmasp I.