National Defense University (MSÜ) Rector Prof. Dr. Erhan Afyoncu made an assessment highlighting the shared history of Türkiye, Azerbaijan and Turkmenistan.
Afyoncu said:

“Three siblings born to the same parents: Türkiye, Azerbaijan and Turkmenistan.”
“Throughout Turkish history, different tribal groups became influential at different times and in different geographies, establishing their own states.”
“The Oghuz, who established the Seljuk, Ottoman, Safavid, Aq Qoyunlu, Qara Qoyunlu, Afshar and Qajar states—among the greatest states in Turkish history—as well as many principalities in Anatolia, Azerbaijan, Iraq and Syria, are the sons of the same father and today rule in the Republic of Türkiye, the Republic of Azerbaijan and Turkmenistan. Approximately half of the 250 million people in the Turkic world are also Oghuz Turks.”
The Oghuz and the Turkic world
The Oghuz are considered one of the largest branches of the Turkic tribes. Turkish as spoken in Türkiye, Azerbaijani Turkish and Turkmen are part of the Oghuz group of Turkic languages.
Türkiye and Azerbaijan are among the members of the Organization of Turkic States (OTS). Turkmenistan participates in the organization as an observer.