It is known that the area around Chiprovtsi has been inhabited since the time of the Thracians and later the Roman Empire, when the local metal deposits were exploited. According to historian V. Velkov, the valley of the Ogosta was inhabited by Thracians since the early 1st millennium BC. According to ancient accounts, the area was populated by the Thracian tribe of the Triballi or a related group of Thracians. The Romans conquered what is today the Bulgarian northwest after 29 BC and consolidated their authority in the region under Emperor Trajan (98–117). There are remains of Roman fortifications around Chiprovtsi, such as the Latin Fortress ruins in the Kula area, where coins dating to the reigns of Marcus Aurelius (161–180) and Commodus (180–192) have been unearthed, and the Big Ruins south of the town. The gold, silver, lead, copper and iron mines brought sizable revenue to the Romans, who took good care to protect these from barbarian attacks.