Reuss , two former German principalities merged into Thuringia 1920. In their last years they existed off two blocks separated by part of Sachsen-Weimar-Eisenach. The southern and larger block or Oberland with Schleiz and Greiz as capitals was east of the Kingdom of Saxony, south of Bavaria, west of Saxe-Meiningen and a Part of Schwarzburg-Rudolstadt and bounded to the northwest by an exclave of Prussian Saxony. The other block, Underland around Gera was bounded by Saxe-Altenburg to the east and west and by Prussia-Saxony to the north.
The government house of Reuss can be traced back to the 12th century. All his male descendants bore the name Henry (in honor of Emperor Henry VI), which required complex numbering. The Plauen line of this family was divided around 1300 between an older branch (extinct 1572) and a younger branch. The latter took the name Reuss from his head, Henry the Russian (so named after a trip to Russia and marriage to a Galician princess). It became Lutheran and divided into three lines in 1564, Elder Reuss, Middle Reuss (extinct 1616) and Younger Reuss. Elder Reuss had his capital at Greiz and other holdings in the Oberland; The younger Reuss owned Unterland with the capital Gera and half of Oberland.
The chiefs of the Elder and the Younger Reuss gained 1673 the rank of a count of Holy Roman Empire ; Elder of the Prince in 1778; and branches of the younger Reuss those of the prince in 1806. Both lines joined 1815 into the German Confederation and became members of the in 1871 German Empire .
The two areas that became free states in 1918 merged on April 4, 1919 to form a People's State of Reuss. This was incorporated into the new Thuringia on May 1, 1920.