In 278 BC, the city, along with the rest of central Anatolia, was occupied by a Celtic group, the Galatians, who were the first to make Ankara one of their main tribal centers, the headquarters of the Tectosages tribe. Other centers were Pessinus, today's Ballıhisar, for the Trocmi tribe, and Tavium, to the east of Ankara, for the Tolistobogii tribe. The city was then known as ''Ancyra''. The Celtic element was probably relatively small in numbers; a warrior aristocracy which ruled over Phrygian-speaking peasants. However, the Celtic language continued to be spoken in Galatia for many centuries. At the end of the 4th century, St. Jerome, a native of Dalmatia, observed that the language spoken around Ankara was very similar to that being spoken in the northwest of the Roman world near Trier.