From Wikipedia
Sardis or Sardes was an ancient city at the location of modern Sart in 
Turkey's 
Manisa Province. Sardis was the capital of the ancient kingdom of 
Lydia,
[1] one of the important cities of the 
Persian Empire, the seat of a 
proconsul under the 
Roman Empire, and the metropolis of the province Lydia in later Roman and 
Byzantine times. 
The earliest reference to Sardis is in 
The Persians of 
Aeschylus (472 BC); in the 
Iliad, the name Hyde seems to be given to the city of the 
Lydian chiefs and in later times Hyde was said to be the older name of Sardis, or the name of its 
citadel. It is, however, more probable that Sardis was not the original capital of the Lydian, but that it became so amid the changes which produced the powerful 
Lydian empire of the 8th century BC.

Map of Sardis and Other Cities within the Lydian Empire
The city was captured by the 
Cimmerians in the 7th century BC, by the 
Persians in the 6th, by the 
Athenians in the 5th, and by 
Antiochus III the Great at the end of the 3rd century BC. In the Persian era, Sardis was conquered by 
Cyrus the Great and formed the end station for the Persian 
Royal Road which began in 
Persepolis, capital of 
Persia. Sardis was the site of the most important Persian satrapy.
[2] During the 
Ionian Revolt, the 
Athenians burnt down the city. Sardis remained under Persian domination until it surrendered to 
Alexander the Great in 334 BC.
The early Lydian kingdom was very advanced in the industrial arts and Sardis was the chief seat of its manufactures. The most important of these trades was the manufacture and dyeing of delicate woolen stuffs and carpets. The stream 
Pactolus which flowed through the market-place "carried golden sands" in early antiquity, which was in reality gold dust out of 
Mount Tmolus. It was during the reign of King 
Croesus that the 
metallurgists of Sardis discovered the secret of separating 
gold from 
silver, thereby producing both metals of a purity never known before.
[3]This was an economic revolution, for while gold nuggets panned or mined were used as currency, their purity was always suspect and a hindrance to trade. Such nuggets or coinage were naturally occurring alloys of gold and silver known as 
electrum and one could never know how much of it was gold and how much was silver. Sardis now could mint nearly pure silver and gold coins, the value of which could be — and was — trusted throughout the known world. This revolution made Sardis rich and 
Croesus' name synonymous with wealth itself. For this reason, Sardis is famed in history as the place where modern 
currency was invented.
Disaster came to the great city under the reign of the emperor 
Tiberius, when in 
AD 17, Sardis was destroyed by an earthquake, but it was rebuilt with the help of ten million 
sesterces from the Emperor and exempted from paying taxes for five years.
[4] It was one of the great cities of western 
Asia Minor until the later 
Byzantine period.