mining = minoan = slavery = romans
Study Reveals That the Balkans Were the Main Supplier of Silver to the Roman Empire for More Than 200 Years, Replacing Hispania Starting in the 3rd Century CE
A recent archaeological study has unearthed a historical truth buried for centuries: the Central Balkans were not a remote marginal province, but rather the main supplier of silver to the Roman Empire for more than 200 years. This is the central conclusion of research by Dr. Dragana Mladenović, published in the Jahrbuch des Deutschen Archäologischen Instituts, which rewrites the economic importance of a region that includes present-day Bosnia and Herzegovina, Serbia, and Kosovo.
While Iberia or Dacia have attracted attention in syntheses on mining in the Roman Empire, the Central Balkans have been underrepresented and, consequently, the importance of the region in the Empire’s metal supply has been critically underestimated.
With this statement, the author begins a journey that corrects a historical bias. The reasons for this neglect are multiple: the Roman and modern administrative division of the region, the prevailing focus on historical sources over archaeological ones, the difficulty of the terrain, and, tragically, the conflicts of the 1990s that still hinder systematic access and study today.
The Conquest of the Subsoil: Roman Gold and Silver
The work focuses on two key provinces: Dalmatia (gold and silver from Bosnia) and Upper Moesia (mainly silver from Serbia and Kosovo). Evidence shows that the Romans wasted no time. Although the conquest was completed around the turn of the era, there are indications that as early as under Augustus the mines were being exploited, possibly through private concessions, before the imperial state took full control.
In the mountains of central Bosnia (such as Vranica and Rošinj), the Romans used advanced hydraulic techniques. They washed gold from the rivers (creating sterile gravel mounds that still give names to towns such as Gomionica, “the pile”), and exploited mountain veins through open-pit mining and a sophisticated hushing system. This technique used large amounts of water stored in tanks and channeled to erode and remove material, separating the gold. Accounts from 19th-century Austro-Hungarian engineers, confirmed by recent studies, describe landscapes literally devastated by this search: hundreds of prospecting pits and large cuts up to 1 km long.
In Srebrenica and Kosovo, the metal was extracted from argentiferous galena, mainly through underground mining. In the Domavia area (modern Srebrenica, Bosnia), modern engineers were astonished to find Roman galleries so well carved that they looked like entrances to underground buildings, with lamp niches, drains, and widenings for passing. To the east, in the Dardania district (Kosovo and southern Serbia), the richest mines were located, such as those of Novo Brdo and Trepča/Stari Trg. Intense medieval and modern exploitation—which supplied one-fifth of Europe’s silver in the 15th century—has almost completely erased the Roman traces, although historical accounts mention thousands of ancient shafts and enormous slag heaps.
The best quantifiable evidence comes from Mount Kosmaj, in Serbia. Here, Roman mining was exclusive, with no medieval continuation, allowing a unique calculation. It is estimated that at least 2.3 million tons of slag were produced in this mountainous district alone. From this amount, it is calculated that approximately 5,500 tons of silver and 680,000 tons of lead were extracted over the exploitation period. To put this in perspective: the average annual silver production in Kosmaj would have been around 22 tons, comparable to that of the famous Laurion district in classical Athens.
The technical sophistication was remarkable. In addition to hydraulic mining, analysis of slag and ingots reveals advanced metallurgical processes. The region’s lead ingots are exceptionally large, some exceeding 250 kg, indicating high-temperature, high-capacity smelting furnaces. In Kosmaj, the cupellation technology used to refine silver was so efficient and uniform that it suggests it was introduced in its final form, not developed in situ.
Unprecedented State Control
The Roman administration of these mines shows a level of intervention and control that the author describes as “unprecedented.” Several elements demonstrate this.
All silver mines and, almost certainly, gold mines were direct property of the emperor, managed by equestrian procurators (rather than freedmen, as was common in Hispania). Leasing to private contractors was minimal.
The military presence was constant, not only for protection but also for technical and administrative support. Under Marcus Aurelius, six new cohorts were created specifically to guard the mining districts. The Danubian limes (frontier) in Upper Moesia remained heavily garrisoned even after it ceased to be a frontier, clearly to protect the river routes by which the metal was transported.
A dense system of portoria (customs) stations was established within the provinces, the publicum portorii Illyrici, surrounding the mining districts. This network, unique in its density, monitored any movement of metal.
From Trajan to Antoninus Pius, low-value bronze coins (semisses and quadrantes) were minted in Rome with legends such as Metalli Dardanici or Aeliana Pincensia. Their function is debated: they may have been designed to facilitate small change in isolated economies or, more likely, to act as a restricted token-coinage within the mining districts to prevent counterfeiting of higher-value currency in a place where metal and technical skill were abundant.
The Great Mining Migration
The scale of operations required a large workforce. Epigraphic evidence suggests significant migrations, possibly encouraged by the state. The most striking case is the large Dalmatian community documented in the gold mines of Alburnus Maior, in Dacia. Were they deportees or voluntary migrants attracted by new opportunities? The author leans toward the latter, especially if, as it seems, gold mining in Dalmatia declined just as the Dacian mines were opening, taking with them their hydraulic mining expertise.
The key moment of the research is the chronological contextualization. The intensification of Balkan mining is no coincidence. It coincides with a turning point in the 2nd century CE: around 160–170 CE, the major silver mines of Hispania (such as Río Tinto) entered decline; the gold mines of Dacia were abandoned after the Marcomannic invasions (167 CE) and finally in 272 CE; and the mines of northwest Hispania also declined in the 3rd century.
For this reason, researchers argue that the Central Balkans were the main source of silver ingots for the Roman Empire from the second half of the 2nd century until at least the first half of the 4th century CE.
Facing the supply crisis in the West, the Roman state turned its attention to the Balkans. Archaeological dating and records of lead contamination in peat bogs confirm a peak of metallurgical activity in the region between 180 and 240 CE. Administrative measures (new cohorts, fiscal reforms, special coinage) were implemented in this same period.
The Severan emperors (193–235 CE) showed particular interest: they visited the region, financed public works in mining areas, and strengthened the Danubian limes. The relocation of imperial mints eastward (such as Siscia or Serdica) under Gallienus and Aurelian seems to have been a strategy to mint coins closer to the silver source. In the chaotic 3rd century, control of these mines was a crucial strategic asset for the “Illyrian emperors” who emerged from the region.
Strategic importance persisted. Constantine was still producing silver donatives in the imperial workshop of Naissus. However, in the 4th century, pressure from invasions and a lack of manpower forced the state to enact laws binding miners and their children to their work. By 386 CE, an edict demanded the return of mining procurators who had fled out of fear of the enemy. Mining then retreated into fortified settlements.
Only the silver mines of Dardania seem to have survived into the 5th century and even, under the patronage of Justinian (who rebuilt Ulpiana as Justiniana Secunda), possibly into the 6th. The definitive end came with the Avar incursions toward the end of the 6th century, when the Empire finally lost control of the Central Balkans.
Dr. Mladenović’s study demonstrates that far from being a periphery, the Central Balkans were the nerve center of the Roman Empire’s silver supply during a critical period of its history, sustaining its currency and finances during the crises of the 3rd century. The research highlights how the wealth of the Balkan subsoil shaped its administration, its military landscape, and its society, attracting investment, migration, and the constant attention of imperial power. It is a reminder that history is written not only on battlefields and in palaces, but also in the depths of the earth.
SOURCES
Mladenović, D. (2025) Roman Gold and Silver Mining in the Central Balkans and Its Significance for the Roman State, Jahrbuch des Deutschen Archäologischen Instituts, 140, pp. § 1–. doi:10.34780/g6w4-86u6
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