Replicas of Celtic coins. In the period of their greatest expansion the Celts became the first people in Central Europe who began to mint their own coins. The Gauls encountered money in the 4th century BCE travelling through Europe as mercenaries. From the 3rd century BCE, when local production exceeded consumption, the first coins were minted mainly from silver and gold. The oldest documented coins are from the 2nd century BCE, the first models copied earlier Madeconian-Greek coins such as staters, drachmas, and tetradrachms. These copies were evenutally replaced with coins depicting Celtic motifs such as a horse. Names of individuals (probably local chieftains) could be seen primarily on older coinage. In the Bohemian territories depictions of wild boars were frequent, as well as a coiled dragon and symbols of the sun. A cup-shaped gold coin now known as the rainbow cup started to be used in the first half of the last century BCE. Unusual Celtic coins were found as part of the largest and most famous hoard of Celtic gold coins in central Europe near the Podmokly village, the Czech Republic, in 1771. Besides rainbow cups, another type of cup-shaped coin found, known as shell stater or golden shells (97% pure gold, weight approx. 6.5 g). The most recent type of a Celtic coin was the large (about 17 g) silver Biatec, which was minted in the southwest of what is now Slovakia approx. 75 – 50 BCE.