Attalid dynasty
Lysimachus, King of Thrace, took possession in 301 BC, but soon after his lieutenant Philetaerus enlarged the town, the kingdom of Thrace collapsed in 281 BC and Philetaerus became an independent ruler, founding the Attalid dynasty. His family ruled Pergamon from 281 until 133 BC: Philetaerus 281–263; Eumenes I 263–241; Attalus I 241–197; Eumenes II 197–159; Attalus II 159–138; and Attalus III 138–133. The domain of Philetaerus was limited to the area surrounding the city itself, but Eumenes I was able to expand them greatly. In particular, after the Battle of Sardis in 261 BC against Antiochus I, Eumenes was able to appropriate the area down to the coast and some way inland. The city thus became the centre of a territorial realm, but Eumenes did not take the royal title. In 238 his successor Attalus I defeated the Galatians, to whom Pergamon had paid tribute under Eumenes I. Attalus thereafter declared himself leader of an entirely independent Pergamene kingdom, which went on to reach its greatest power and territorial extent in 188 BC.