A Silver Tetradrachm of Alexander the Great, Mint of Amphipolis (modern Amfípolis, northern Greece), 336-323 BCE. Obverse: Head of Alexander The Great as Hercules, or Herakles, wearing a lion skin. Reverse: Zeus enthroned, facing left, holding a scepter in one hand and an eagle in the other. The word AMPHIPOLIS is imprinted behind Zeus. Coin encased in modern 18K Gold and attached to multiple strings of modern seed pearls. According to the British Museum, the kings of Macedon began to issue coinage in the early fifth century BC. Although northern Greece was rich in precious metal resources, the Macedonian kings were not initially powerful enough to gain constant access to mines. When Philip II came to the throne in 359 BC he embarked upon an ambitious plan of conquest. In nearby Thrace the cities of Amphipolis and Crenides both became part of his empire. Amphipolis had rich silver mines, while Crenides, which Philip renamed Philippi, had wealthy gold mines. Philippi alone was said to have provided him with 1000 talents (26,000 kg) per year. This enabled Philip to produce a vast series of gold coins which became one of the staple currencies of the Greek world. Building upon his father's success in Greece, Alexander III (Alexander the Great, reigned 336-323 BC) set about the conquest of the Achaemenid Persian Empire. By the time of his death at the age of 31, he ruled most of the known world from Greece to Afghanistan. Initially Alexander continued to mint Philip's gold and silver coins. Soon, however, the need for a silver coinage that could be widely used in Greece caused him to begin a new coinage on the Athenian weight-standard. His new silver coins, with the head of Herakles on one side and a seated figure of Zeus on the other, also became one of the staple coinages of the Greek world. They were widely imitated within the empire he had forged.