Seuthes I was king of the Odrysian Thracians

Thracians

The ancient Thracians were a group of Indo-European tribes inhabiting areas including Thrace in Southeastern Europe. They spoke the Thracian language – a scarcely attested branch of the Indo-European language family...

 from 424 BC until 410 BC. He was the nephew of Sitalces. He is infamous for the fact that he was bribed by Perdiccas II of Macedon

Perdiccas II of Macedon

Perdiccas II was a king of Macedonia from about 454 BC to about 413 BC. He was the son of Alexander I and had two brothers.-Background:After the death of Alexander in 452, Macedon began to fall apart. Macedonian tribes became almost completely autonomous, and were only loosely allied to the king...

, which directly lead to the end of Sitalces' campaign in Macedon

Macedon

Macedonia or Macedon was an ancient kingdom, centered in the northeastern part of the Greek peninsula, bordered by Epirus to the west, Paeonia to the north, the region of Thrace to the east and Thessaly to the south....

. After he became king, Seuthes doubled the tribute of the Greek cities on the coast. In 411 BC Seuthes led a campaign against Athens

Athens

Athens , is the capital and largest city of Greece. Athens dominates the Attica region and is one of the world's oldest cities, as its recorded history spans around 3,400 years. Classical Athens was a powerful city-state...

, which was not very successful. Seuthes died in 410 BC after a serious illness. Amadocus succeeded him as ruler of the Odrysian kingdom

Odrysian kingdom

The Odrysian kingdom was a union of Thracian tribes that endured between the 5th and 3rd centuries BC. It consisted largely of present-day Bulgaria, spreading to parts of Northern Dobruja, parts of Northern Greece and modern-day European Turkey...

.