been influenced by their non-Iranian neighbors, especially Caucasians and Russians. Azerbaijanis in both Iran and the Republic of Azerbaijan are mostly Shiite Muslims. Azerbaijanis in Iran and in the Republic of Azerbaijan celebrate Nowruz, the Iranian new year, at the arrival of spring. Azerbaijan has a distinct music that is tightly connected to the music of other Iranian peoples such as Persian music and Kurdish music, and also the music of the Caucasian peoples. Although the Azerbaijani language is not an official language of Iran it is widely used, mostly orally, among the Iranian Azerbaijanis. Literature Many poets that came from Azerbaijan wrote poetry in both Persian and Azerbaijani. Renowned poets in Azerbaijani language are Nasimi, Shah Ismail I (who was known with the pen-name Khatai), Fuzuli, Nasimi and Jahan Shah were probably born outside what is now Iranian Azerbaijan. Azerbaijani was the dominant language of the ruling dynasties of the Turkic rulers of the area such as the Ak Koyunlu, Kara Koyunlu and later it was used in the Safavid court until Isfahan became capital and religious dignitaries, military. In the 16th 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 and Tahmasp I. In the span of the 17th century, 18th and 19th century, Fizuli's unique genres as well Ashik poetry were taken up by prominent poets and writers such as Qovsi Tabrizi, Shah Abbas Sani, Khasta Qasim, Mirza Fatali Akhundov, Seyid Abulgasim Nabati, Ali Mojuz and others. An influential piece of post-World War II Azerbaijani poetry, Heydar Babaya Salam (Greetings to Heydar Baba) was written by Azeri poet Mohammad Hossein Shahriar. This poem, published in Tabriz in 1954 and written in colloquial Azerbaijani, became popular among Iranians and the people of Azerbaijan Soviet Socialist Republic. In Heydar Babaya Salam, Shahriar expressed his identity as an Iranian attached to his homeland, language, and culture. Heydar Baba is a hill near Khoshknab, the native village of the poet. Azerbaijan is mentioned favorably on many occasions in Persian literature by Iran's greatest authors and poets. Examples: گزیده