Due to the lack of written information regarding the Getae-Dacians'

Dacia

In ancient geography, especially in Roman sources, Dacia was the land inhabited by the Dacians or Getae as they were known by the Greeks—the branch of the Thracians north of the Haemus range...

 history, many important names related to their civilization remain either unknown or controversial. The controversy regarding the name of this king was prompted after the discovery of golden coins inscribed with the word KOSON in Greek characters

Greek alphabet

The Greek alphabet is the script that has been used to write the Greek language since at least 730 BC . The alphabet in its classical and modern form consists of 24 letters ordered in sequence from alpha to omega...

. Such coins were discovered in great numbers in Transylvania

Transylvania

Transylvania is a historical region in the central part of Romania. Bounded on the east and south by the Carpathian mountain range, historical Transylvania extended in the west to the Apuseni Mountains; however, the term sometimes encompasses not only Transylvania proper, but also the historical...

 and the discovery captured the attention of writers starting the 16th century. Thus, there are comments from Erasmus of Rotterdam

Rotterdam

Rotterdam is the second-largest city in the Netherlands and one of the largest ports in the world. Starting as a dam on the Rotte river, Rotterdam has grown into a major international commercial centre...

 in 1520 and Stephanus Zamosius

Szamosközy István

Szamosközy István was a Hungarian humanist and historian.-Life:Szamosközy was born in Kolozsvar to a Calvinist family. He completed his studies at Heidelberg and Padova. In 1593 he returned to Hungary and started to work in Gyulafehervar for the archive of the Transylvanian court...

 (István Szamosközy) in 1593.
Coins inscribed KOSON were discovered in several large stashes in Transylvania

Transylvania

Transylvania is a historical region in the central part of Romania. Bounded on the east and south by the Carpathian mountain range, historical Transylvania extended in the west to the Apuseni Mountains; however, the term sometimes encompasses not only Transylvania proper, but also the historical...

. The first group was discovered in 1543, and contained several thousands coins and objects made of gold. It was rumored that this stash was revealed in a bolted chamber under the river Strei, identified as the river Sargetia, and also mentioned by Dio Cassius

Dio Cassius

Lucius Cassius Dio Cocceianus , known in English as Cassius Dio, Dio Cassius, or Dio was a Roman consul and a noted historian writing in Greek...

. Further research disproved this, and placed the treasure in one of the Dacian castles

Dacian Fortresses of the Orastie Mountains

Built in murus dacicus style, the six Dacian Fortresses of the Orăștie Mountains, in Romania, were created in the 1st centuries BC and AD as protection against Roman conquest....

 in the Orăştie

Orastie

Orăștie is a city in Hunedoara County, south-western Transylvania, Romania.-History:7th–9th century – on the site of an old swamp , which today is the old center of town, it was a human settlement whose traces have been scattered into the X-th century by the construction of the first...

 mountains, probably in Sarmisegetusa.

The conventional view that these coins were struck by a Thracian dynast named Koson striking on behalf of Brutus was first proposed by Theodor Mommsen. Mommsen based his theory on Appian' s statement (B Civ. IV.10.75) that Brutus struck coins from the gold and silver provided to him by the wife of a Thracian dynast. The coins' similarity to known Roman types of the period, in particular the issue Brutus struck as a moneyer in 54 BC (Crawford 433/1), and Mommsen's (and others) misreading of the obverse monogram seemed to support this conclusion. Max Bahrfeldt ("Über die KOΣΩN-Münzen," Berliner Münzblätter 1912), however, cogently challenged this interpretation, arguing instead a connection to Coson-Cotiso(n), a Getic king with whom Octavian had apparently been arranging an alliance-by-marriage (Suetonius, Aug. 63.2; cf. Horace, Carm. II.18.8; Flor. II.28.18). Nonetheless, Mommsen's academic reputation and the appeal of associating these coins with Caesar's assassin favored the earlier interpretation. Thus, this attribution has largely been unchallenged (but see M. Crawford, CMRR, p. 238: "A remarkable issue of gold staters, imitated from the denarii of M. Brutus.... Showy and useless, it was probably produced in the area of modern Transylvania in the second half of the first century.").

Re-examining the evidence, Octavian Iliescu has argued in support of Bahrfeldt's interpretation based on the following reasons: first, hoards as well as individual specimens of these coins can be traced for the most part to Transylvania (northern Romania), rather than Thrace (southern Bulgaria); second, the average weight of known specimens conforms not to the aureus-standard of 8.10 gm established by Julius Caesar in 46 BC, and at which Brutus struck coins for his troops, but to that of the staters struck on behalf of Mithradates VI during the First Mithradatic War; third, the coin types do not directly copy the corresponding types of Brutus' denarius, but combine the type's reverse with the reverse of a denarius of Q. Pomponius Rufus struck three decades earlier. The discovery of many coins in a number of archaeological excavations that include different Roman types from various periods further undercuts the specific historical connection to the use of the Brutus-type. Moreover, the monogram that has been read to achieve L BR, BR, or, in the case of Barclay Head, OΛB, and thus associate the coinage with Brutus or Olbia, may also be read as a BA monogram for BAΣIΛEΩΣ. Such a BA monogram is known to have been used for the Thracian king Rhoemetalces I.

Rendered as Cotiso(n) in the literary sources, this name can be reconciled with Coson as a transcribal error on the part of the textual copyist, making Coson-Cotiso(n) one and the same: a local Geto-Dacian king for whom these staters, and perhaps associated silver coins, are the only known coinage. It is this king Cotiso(n) to whom Octavian had sought to arrange an alliance-by-marriage (Suetonius, op. cit.), with his daughter Julia marrying Koson's son, and himself, Koson's daughter. This negotiation angered Mark Antony, to whose son Julia had originally been promised, and exacerbated the rift between Octavian and himself. The local usage of Roman coin types in the region during the last century BC demonstrates the economic ties between Dacia and Rome, but the struggle between Antony and Octavian revealed the region's strategic and diplomatic significance, by increasing the local king's power and prestige and affording him the opportunity to strike his own coins.