Seljuks in Dobruja
Seljuk Turks in Anatolia (most of modern Turkey) were defeated by the Mongols in the Battle of Kösedağ (1243). During the rest of the century, they were more or less puppets of the Mongols. In 1257, the Mongols divided Seljuk lands between two brothers, Izzettin Keykavus II and Kılıç Aslan IV. Moreover, İzzettin was forced to obey his younger brother. Although İzzettin tried to struggle, in 1262 he had to flee from Antalya, a port in Seljuk territory to Byzantine territory with a large partisan group.
Settlement in Dobruja 
Byzantine Emperor Michael VIII Palaiologos, who had just recaptured Constantinople (modern İstanbul) from the Latin Empire, was a relative of İzzettin. However, he had allied himself with the Mongols of Baghdad (who’ll soon be called Ilkhanids) and instead of supporting İzzettin, he kept İzzettin as a refuge and settled İzzettin's partisans to the area between Varna, now in Bulgaria and the estuary of the Danube (1262–1263), a country which later on was named as Dobruja (Turkish: Dobruca). After an unsuccessful revolt in Byzantine Empire, İzzettin fled to Crimea, which was under Golden Horde rule. But his followers stayed in the area allocated to them. Their new leader was Sarı Saltık Dede, whose tomb is in Babadag, Romania.
In 1307, a part of Dobruja Turks under Ece Halil returned to Anatolia. They settled in the northwest Anatolian beylik of Karesi, which became later a part of the Ottoman Empire. The rest stayed in Dobruja. While keeping their language, they converted to Christianity. They maintained their political independence from Second Bulgarian Empire. Their small principality of Dobruja lived until the Ottoman conquest in 1417. They are believed to be the anchestors of modern Gagauz people. The name Gagauz may be a reminiscence of the name Kaykavus.
See also 
- Prof. Yaşar Yüce-Prof. Ali Sevim: Türkiye tarihi Cilt I, AKDTYKTTK Yayınları, İstanbul, 1991 p 131
- Kate Fleet-Machiel Kiel:Cambridge History of Turkey Vol 1, Cambridge Press, ISBN 978-0-521-62093-2 p.141
- Prof. Yaşar Yüce-Prof. Ali Sevim: Türkiye tarihi Cilt I, AKDTYKTTK Yayınları, İstanbul, 1991 p 207
- Claude Cahen: Pre Ottoman Turkey (j.Jones Willims, Taplinger Publishing Co., New York, 1968, p.279