Cotini was a Celtic tribe

Celt

The Celts were a diverse group of tribal societies in Iron Age and Roman-era Europe who spoke Celtic languages.The earliest archaeological culture commonly accepted as Celtic, or rather Proto-Celtic, was the central European Hallstatt culture , named for the rich grave finds in Hallstatt, Austria....

 most probably living in today's Slovakia

Slovakia

The Slovak Republic is a landlocked state in Central Europe. It has a population of over five million and an area of about . Slovakia is bordered by the Czech Republic and Austria to the west, Poland to the north, Ukraine to the east and Hungary to the south...

, and (according to occasional opinions) in Moravia

Moravia

Moravia is a historical region in Central Europe in the east of the Czech Republic, and one of the former Czech lands, together with Bohemia and Silesia. It takes its name from the Morava River which rises in the northwest of the region...

 and southern Poland

Poland

Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...

. They were probably identical or constituted a significant part of the archaeological Púchov culture

Púchov culture

The Púchov culture was an archaeological culture named after site of Púchov-Skalka in Slovakia. Its probable bearer was the Celt Cotini tribe. It existed in northern and central Slovakia between the 2nd century BCE and the 1st century CE...

, with the center in Havránok

Havránok

Havránok is an important archaeological site in northern Slovakia. It is located on a hill above the Liptovská Mara water reservoir around 2 km from the village of Bobrovník, about halfway between Ružomberok and Liptovský Mikuláš in the Liptov region...

.

The tribe was first time mentioned in 10 BC in the Elogium of Tusculum. According to Tacitus

Tacitus

Publius Cornelius Tacitus was a senator and a historian of the Roman Empire. The surviving portions of his two major works—the Annals and the Histories—examine the reigns of the Roman Emperors Tiberius, Claudius, Nero and those who reigned in the Year of the Four Emperors...

, both Sarmatians

Sarmatians

The Iron Age Sarmatians were an Iranian people in Classical Antiquity, flourishing from about the 5th century BC to the 4th century AD....

 (present-day Ukraine) and Quadi

Quadi

The Quadi were a smaller Germanic tribe, about which little is definitively known. We only know the Germanic tribe the Romans called the 'Quadi' through reports of the Romans themselves...

 (present-day southwestern Slovakia, and eastern Czech Republic) extracted tribute from the iron

Iron

Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

 mines of the Cotini in the 1st century AD. The Cotini are later mentioned in connection with the Marcomannic Wars

Marcomannic Wars

The Marcomannic Wars were a series of wars lasting over a dozen years from about AD 166 until 180. These wars pitted the Roman Empire against the Marcomanni, Quadi and other Germanic peoples, along both sides of the upper and middle Danube...

: Around 172 AD, they did not help Romans

Roman Empire

The Roman Empire was the post-Republican period of the ancient Roman civilization, characterised by an autocratic form of government and large territorial holdings in Europe and around the Mediterranean....

 in their fight against Marcomanni

Marcomanni

The Marcomanni were a Germanic tribe, probably related to the Buri, Suebi or Suevi.-Origin:Scholars believe their name derives possibly from Proto-Germanic forms of "march" and "men"....

. To punish them, Marcus Aurelius had moved (all?) the Cotini to Lower Pannonia

Pannonia

Pannonia was an ancient province of the Roman Empire bounded north and east by the Danube, coterminous westward with Noricum and upper Italy, and southward with Dalmatia and upper Moesia....

, which happened not later than 180 AD. In Lower Pannonia, they are mentioned as "cives Cotini" - the Cotini people - in 223-251 AD.