Bayat (Bayat tayfası; بیات; Bayat boyu; Baýat taýpasy) is one of the Oghuz tribes in Turkmenistan, Iran, Turkey, Azerbaijan, Iraq, Afghanistan, and Syria. When Oghuz Turks started to migrate from the Aral steppes to Khorasan in the 11th and 13th centuries, Bayat people spread throughout the region. They are sub-ethnic groups of Turkmens and Azerbaijanis. Bayats are Muslim and speak a southern dialect of Azerbaijani language in Azerbaijan and Iran, or their own dialect of Turkish in Turkey, and Ersari dialect of Turkmen in Turkmenistan and Uzbekistan. The ancient Turkmen proverb says: "Kayi and Bayat tribes shall lead the people" (Turkmen: "Il başy - gaýy-baýat"). Initially, the ethnonym Bayat was mentioned as an Oguz tribe in the 11th century by the Turkic historian Mahmud Kashgari. Bayat - an Oghuz Turkic tribe, who stood together with the Kayi tribe at the head of all 24 Oguz tribes - "Il bashi Kayi-Bayat." In the traditions of the Turkic tribes, the origin of this tribe is traced to Bayat - the grandson of Oghuz-Khan. In the book of the Khan and historian of the Khiva Khanate, Abu al-Ghazi Bahadur, "Genealogy of the Turkmens," the meaning of the name of the tribe is given as "rich". Bayat was the second son of Gun-Khan, who was the first son of Oguz-Khan. According to the work of the historian, Rashid-al-Din Fazl-Allah, "Oghuz-nameh", which is part of his extensive historical work Jami' al-tawarikh (Collection of Chronicles), the name Bayat means "rich, full of grace". On the territory of Kievan Rus, Bayats are recorded as part of the Oghuz tribes in chronicles of the 10th-12th centuries by the name of bouts. Bayat is the name of an originally Turkic clan in Turkey, Azerbaijan and Iran which traces its origin to the 12th century. When Bayat clan started to migrate from the Aral steppes, their first destination was the city of Nishapur in the south of Khorasan, a state in the north-east of Iran. The Bayat clan moved in the 13th century to three different locations after attacks by Mongol forces.