The County of Diez (sometimes Dietz, German: Grafschaft Diez) was a county of the Holy Roman Empire, centred on the at Diez in Lahngau (in the modern German states of Hesse and Rhineland-Palatinate). The county is first attested in 1073 and seems to have been created from the territory of the Conradine dynasty after they relocated to Swabia. The Counts rose to prominence in the second half of the twelfth century as close partisans of the Hohenstaufen dynasty. During this period, it was known as the "Golden County".