You will not find the name Amphipolis in the Hebrew or Aramaic language. The name is Greek, so that is why you don't read about it in the Bible until the New Testament. The name is the same in Latin. English adopted it as it's own language since it is a name
Amphipolis was founded by Athenian settlers in 437 BC. It was a battle site between Spartans and Athenians in 422 BC. In about 300 years it became the capital of the first administrative district of Macedonia. In 1956 Greek archaeologist excavated the city finding coins, inscriptions, remains of a Roman aqueduct, tombs, walls, bridge, and gymnasium. Five churches were discovered.
Amphipolis is a city in Macedonia found in the Bible. It is mentioned in Paul and Silas' missionary journey. It was a major town about 33 Roman miles from Philippi and three from the sea. It was placed on a plateau overlooking the valley of the River Strymon.
Amphipolis and Apollonia were connector cities in Paul and Silas' mission journey. Basically the scripture implies it is where they may have slept and ate before continuing on to Thessalonica. In Thessalonica they went to the Jewish Synagogue to preach.
Maybe there was no opportunity in Amphipolis or maybe because it was so saturated in the Greek culture they didn't have an opportunity to stop and talk about the Gospel. Maybe God did not have them stop because their purpose laid in Thessalonica.
Acts 17:1-4