Magnesia or Magnesia on the Maeander was an ancient Greek city in Ionia, considerable in size, at an important location commercially and strategically in the triangle of Priene, Ephesus and Tralles. The city was named Magnesia, after the Magnetes from Thessaly who settled the area along with some Cretans. It was later called "on the Meander" to distinguish it from the nearby Lydian city Magnesia ad Sipylum. It was earlier the site of Leucophrys mentioned by several ancient writers.
The territory around Magnesia was extremely fertile, and produced excellent wine, figs, and cucumbers. It was built on the slope of Mount Thorax, on the banks of the small river Lethacus, a tributary of the Maeander river upstream from Ephesus. It was 15 miles from the city of Miletus. The ruins of the city are located west of the modern village Tekin in the Germencik district of Aydın Province, Turkey.
Magnesia lay within Ionia, but because it had been settled by Aeolians from Greece, was not accepted into the Ionian League. Magnesia may have been ruled for a time by the Lydians, and was for some time under the control of the Persians and subject to Cimmerian raids.