The history of Anatolia is an interesting one. There were a number of prominent ancient powers that held historical importance. I won't bore you with the details of Anatolia's distant past, other than to note that cities like Çatalhöyük in the Neolithic period developed, and groups such as the Hittites and Luwians rose to prominence in the Bronze and Iron ages, and the ancient city of Troy (from the Trojan War) was also in this region.

There is rarely a complete power vacuum anywhere where there are people. If large empires are not present, smaller city-state style kingdoms will arise and occupy that power vacuum, often without changing the overall global power scale (i.e. being relatively invisible on a global scale).

Prior to the Ottoman Empire and the reign of Osman I, this exact situation was the case across Anatolia. The land was divided up into a number of beyliks ruled by beys. These were essentially petty kingdoms ruled relatively independently (though they may have been nominally under the suzerainty of a larger Mongol or Islamic entity, the Seljuk Turks from central Asia, they were effectively independent)(see Mehmet Fuat Köprülü, Gary Leiser-The origins of the Ottoman Empire, p.33. This was the situation immediately prior to the rise of Osman I.

Prior to the beyliks, the area was under Mongol control, and was a frontier to the conflicts between the remnants of the Christian Byzantine empire and the Muslim Seljuk Turks, with sovereignty going back and forth a couple of times between the 1100s and the 1300s see H. M. Balyuzi Muḥammad and the course of Islám, p.342 and Clifford Edmund Bosworth-The new Islamic dynasties: a chronological and genealogical manual, p.234.

Prior to this, Anatolia (aka Asia Minor) was part of the Byzantine and Roman empires, and the area was a center of conflict between the Byzantines and Romans and the various groups that arose in the greater Mesopotamian area, including the Sassanid Persians, and the Parthians before them.

The Romans basically were bequeathed the area from one of the Hellenistic (that's basically the Greek empire that came out of Alexander the Great's conquest of the known world) Attalid kingdoms. These Greek kingdoms were taken by Alexander from the Achaemenid Persians who ruled most of the Near East in the 500s to 300s BC. Prior to this, Anatolia was mainly ruled by a large number of localized kingdoms, such as Lydia, Lycia, Caria, Phrygia, Cappadocia, and many others.

That is an extremely overviewy history of power in Anatolia, back to the Classical period. If you have questions, I would try to answer them, but I am not an expert in these time periods or really this geographical space. If anyone has some academic training in this region and time period and would like to correct or clarify anything I say here, please do so. If anyone would like some additional sources for any of my claims, I can provide them as asked, but because this topic covers so much time, there would be quite a lot.