The Oghuz languages are a sub-branch of the Turkic language family, spoken by approximately 108 million people. The three languages with the largest number of speakers are Turkish, Azerbaijani and Turkmen, which combined account for more than 95% of speakers.
Swedish turcologist and linguist Lars Johanson notes that Oghuz languages form a clearly discernible and closely related block within the Turkic language family as the cultural and political history of the speakers of Oghuz languages has linked them more closely up to the modern age.
The term "Oghuz" is applied to the southwestern branch of the Common Turkic languages. It is in reference to the Oghuz Turks, who migrated from the Altay Mountains to Central Asia in the 8th century and further expanded to the Middle East and to the Balkans as separate tribes.
The Oghuz languages currently spoken have been classified into three categories based on their features and geography: Western, Eastern, and Southern.
The extinct Pecheneg language was probably Oghuz, but as it is poorly documented, it is difficult to further classify it within the Oghuz family; it is therefore usually excluded from classification.
The Oghuz languages share a number of features that have led linguists to classify them together. Some of the features are shared with other Turkic languages, and others are unique to the Oghuz family.
The remarkable similarity between Oghuz languages may be demonstrated through the sentence, which employs a verbal noun in the dative as a link between the main verb and auxiliary. This feature is universally shared by all Oghuz languages. Turcologist Julian Rentzsch uses this particular sentence in his work titled "Uniformity and diversity in Turkic inceptive constructions":
English: 'The dead man rose, sat down and began to speak.'