The House of Wettin (Haus Wettin) was a dynasty of German kings, prince-electors, dukes, and counts that once ruled territories in the present-day German states of Saxony, Saxony-Anhalt and Thuringia. The dynasty is one of the oldest in Europe, and its origins can be traced back to the town of Wettin, Saxony-Anhalt. The Wettins gradually rose to power within the Holy Roman Empire. Members of the family became the rulers of several medieval states, starting with the Saxon Eastern March in 1030. Other states they gained were Meissen in 1089, Thuringia in 1263, and Saxony in 1423. These areas cover large parts of Central Germany as a cultural area of Germany.
The family divided into two ruling branches in 1485 by the Treaty of Leipzig: the Ernestine and Albertine branches. The older Ernestine branch played a key role during the Protestant Reformation. Many ruling monarchs outside Germany were later tied to its cadet branch, the House of Saxe-Coburg and Gotha. The Albertine branch, while less prominent, ruled most of Saxony and played a part in Polish history.
Agnates of the House of Wettin have, at various times, ascended the thrones of the United Kingdom, Portugal, Bulgaria, Poland, Saxony, Mexico and Belgium. Only the Belgian line retains their throne today.
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). He was most probably based in the Liesgau (located at the western edge of the Harz). Around 1000, the family acquired Wettin Castle, which was originally built by the local Slavic tribes (see Sorbs), after which they named themselves. Wettin Castle is located in Wettin in the Hassegau (or Hosgau) on the Saale River. Around 1030, the Wettin family received the Eastern March as a fief.
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.