The oldest member of the House of Wettin who is known for certain is Theodoric I of Wettin, also known as Dietrich, Thiedericus, and Thierry I of Liesgau (died c. 982).
The prominence of the Wettins in the Slavic Saxon Eastern March (or Ostmark) caused Emperor Henry IV to invest them with the March of Meissen as a fief in 1089.