The Anatolian beylik of Germiyan with its capital in Kütahya was one of the prominent frontier principalities established by Kurds and Turkmens after the decline of Seljuq Sultanate of Rûm. According to Agoston and Masters Germiyanoğulları were Turkmens who had immigrated to the west because of Mongol pressure in the second half of the 13th century.
For a brief period in the second half of the 14th century, Germiyan Dynasty was second only to Karamanid Dynasty in its rising power. But they were later taken over by the neighboring Osmanoğlu dynasty, who were to found the Ottoman Empire later.
Germiyans played a crucial role in settling Turkish populations along the coastal regions of the Aegean Sea, the founders of the Beyliks of Aydin, Sarukhan, İnançoğlu and Menteşe having started out as Germiyan commanders.
Because of various factors arising from the Mongol invasion, their branch of the clan had left the regions of Fars and Kirman, and headed west into Anatolia, having remained for a time around Malatya, and then moving to the Kütahya area, where their beylik was formed rather rapidly.