Oghur Turkic branch is distinguished from Proto-Turkic somewhere between 3000 BC and 500 BC, we really are not sure, and has no mutual intelligibility with other Turkic dialects. But we know that a group of Turkic peoples who called themselves Oghur migrated slowly to Ural mountains’ area which they first contacted with Ugric peoples like Hungarians or Mari. Oghur branch is also named as “lir” or -”r Turkic” while Common Turkic is “shaz” or “-z Turkic” because of a phonetic change rule which is called “rhotacizm” and most probably Oghur language were the most closest to Proto-Turkic. And we know that Oghuz name is much more older than the name Turk and with rhotasizm effect it turned from Oghur to Oghuz somewhere between 100–500 AD. So this shows us that a small group of Oghur people decided to migrate to west while the other decided to stay and with phonetical changes in 100–500 AD, name of the “stayers” slowly became Oghuz.
Horse was tamed with Botai Culture which will be evolved to Afanasievo then Andronovo Culture. The Andronovo Culture which emerged 2000 BC most probably started with Oghurs then spreaded to Scythians which was an Indo-European group then expanded through Siberian steppes to today’s Mongolia. Andronovo culture (which will evolve to Karasuk then Tagar culture) started a semi-nomadic life and created the Turco-Mongol tradition and the rest is not our subject. Scythia was most probably a confederation of Turkic peoples and Iranian peoples while the majority was Iranian. Then the Huns came. Huns were most probably a confederation of Mongolic peoples, Tungusic peoples and Turkic peoples, mostly Oghurs but some Iranian folks like Alans (what is left from Scythians), some Germanic clans like Lombards and Ugric peoples were a part of it too. Oghur language spreaded in today’s Ukraine. In 5th century AD, Bulgar name came out. Bulgars were a Oghur Turkic nomadic people. Upon Attila’s death, Bulgar tribes that later formed the Bulgars had retreated east into the Black Sea-Caspian Steppe. The western Bulgar tribes joined the Avar Khaganate, while the eastern Bulgars came under the Western Turkic Khaganate. By the end of the 6th century, Old Great Bulgars came in sight which were Oghur branch speakers. Old Great Bulgaria was established by Kubrat and First Bulgar Empire established in today’s Bulgaria by Asparuh, son of Kubrat. Some Bulgars migrated to the Volga area which is called Chuvashia today, Ugric peoples like Mari and ancestors of Hungarians were living already in the area when Bulgars migrated, Ugric languages and Turkic languages effected each other a lot until the Hungarian Migration began in 10th century. (A little trivia, root of the name Hungarian is actually Onogur or Onoghur which means Ten Oghurs, as I said, Ugric peoples and Turkic peoples effected each other a lot) Some of Volga Bulgars converted to Islam by the 10th century and are assimilated under other Turkic groups, mostly in Tatar identity while today’s Chuvash people who speaks Chuvash language which is the only surviving Oghur language kept their identity. Bulgars of First Bulgar Empire are assimilated under Slavic peoples, becoming todays Bulgarians, Old Great Bulgars disestablished by Khazar Khanate. That’s the story.
Lastly, I’m leaving the tamgas(marks) of Dulo Clan of Oghurs that established First Bulgar Empire and Old Great Bulgaria and Kayı Clan of Oghuzes which established Ottoman Empire below.