The Reuß family had Erkenbert, Herr von Weida (about 1122) as their first ancestor ("Stammvater"). Heinrich VI., Empror of the Holy Roman Empire bestowed the family the Reichsvogteien Plauen (1569 to Kursachsen), Weida (1411 to Meißen) und Gera; he is reportedly the eponym of all Reuß´ Heinrichs.
Heinrich, Vogt of Plauen (died before 1296), married a russian princess - he was the first to bear the name of Reuß (meaning "Russian").
1564 the Reuß properties were divided by succession into the Ältere Linie (Untergreiz), Mittlere Linie (Obergreiz) und Jüngere Linie (Gera).
In 1616 the Mittlere Linie (Middle Line) died out, it´s property being transferred to both other Lines. The Older Line was promoted Reichsfürst in 1778; the Younger Line in 1790.
Both lines became federal states of the Norddeutscher Bund (North German Confederation) in 1866 and federal states of the German Empire in 1871.
1902-1918 Heinrich XXIV. of Reuß ä.L. was unable to run the government due to an accident in his childhood; the Older Line had Fürst Heinrich XIV. jüngere Linie (1902-1908) and Heinrich XXVII. of Reuß j.L. (1908-1918) as regent.
Both lines existed as sovereign rulers until 1918, when they had to abdicate.
All male descendants of all Reuß lines were named Heinrich.
The older line counted to 100 in roman figures (C); the younger line began with "one" (I) at the beginning of each century.