More significantly, the earliest genealogies written by the Ottomans did not include any reference to Kayı descent at all, indicating that it may have been fabricated at a later date.

[16] In the 10th century, the Central Asian Oghuz Yabgu State was headed by supreme leaders (or Yabghu) who belonged to the Kayı tribe.

[17] According to Soviet archaeologist and ethnographer Sergey Tolstov, part of the Kayi tribe moved in the Middle Ages from Central Asia to modern day Ukraine, they are known in the Rus' chronicle as kovuy and kaepichi as one of the tribes that formed the Turkic tribal confederation called the Black Klobuks,[a] who were allies of the Rurik dynasty of the Rus' Khaganate;[19] Golden however considers the Kaepichi to be descendants of the Mongolic or para-Mongolic Qay instead.

[20][21] Soviet and Russian linguist and turkologist A. V. Superanskaya associates the Kayı tribe with the origin of the name of the city of Kyiv;[22] however, Canadian Ukrainian linguist Jaroslav Rudnyckyj connects the name Kyiv to the Proto-Slavic root *kyjь, which should be interpreted as meaning 'stick, pole' as in its modern Ukrainian equivalent Кий; therefore, the toponym should in that case be interpreted as 'palisaded settlement'.

[24] In Turkmenistan, the Kayı tribe is one of the main divisions of the Gökleň Turkmens living in the Balkan velayat and consists of the following clans: adnakel, ak kel, alatelpek, bagly, barak, burkaz, ganjyk, gapan, garabalkan, garawul, garagol, garagul, garadaşly, garakel, garga, garyşmaz and others.