The progenitor of the family, Count
Poppo I of Blankenburg (c. 1095 – 1161 or 1164) probably was related to the
Rhenish Reginbodonid dynasty of Archbishop
Siegfried of Mainz (d. 1084), a cadet branch of the Franconian
Conradines. His uncle
Reinhard of Blankenburg was
Bishop of Halberstadt from 1107 onwards and provided him with large estates in the Eastphalian
Harzgau region between the
Ilse and
Bode rivers. Poppo was first documented as
comes in an 1128 deed, serving the Saxon duke
Lothair of Supplinburg and his
Welf successors. His son Conrad was the first descendant to call himself
Comes de Regenstein in 1162, while his brother Siegfried continued to rule as
Count of Blankenburg. After the deposition of the Saxon duke
Henry the Lion in 1180, the Regenstein counts were temporarily arrested by the forces of Emperor
Frederick Barbarossa, but were reconciled with the
Hohenstaufen monarch soon after. After a lengthy feud
Heimburg Castle, built about 1170 by King
Henry IV and soon after devastated during the Saxon Rebellion, was acquired by the Regenstein counts in the early 14th century. The Regenstein-Heimburg branch re-united the Regenstein and Blankenburg estates in 1343, under the rule of the most renowned Count (1310–49), who since the 1330s was frequently in dispute with the leaders of the surrounding estates like the Halberstadt bishops and the
Abbesses of Quedlinburg; he was finally assassinated by the henchmen of Bishop
Albert II of Halberstadt. These tales were romanticised in the
ballad The Robber Count () by
Gottfried August Bürger, melodized by
Johann Philipp Kirnberger and the novel of the same name by
Julius Wolff. In the 15th century the comital family finally relocated its seat to
Blankenburg Castle; the Regenstein fortress lapsed and was left to ruin. In order to gain greater independence from the Halberstadt bishops, the counts turned
Protestant in 1539. The last scion of the comital family, Count John Ernest, died in 1599. With Blankenburg, the County of Regenstein fell back to the Prince-Bishopric of Halberstadt. Shortly thereafter Blankenburg and Regenstein were separated: Regenstein remained with the secularised
Principality of Halberstadt, while the remaining
County of Blankenburg was annexed and held by the Dukes of
Brunswick-Wolfenbüttel. ==Counts of Regenstein==