In 1162
Cunradus Comes de Regenstein (Conrad, Count of Regenstein), the son of Count
Poppo I of Blankenburg from the House of
Reginbodonen, was documented for the first time by name, thus establishing the line of Reinstein-
Blankenburg.
Heimburg came into their possession in the 14th century as a
fief and founded the Younger Line of Reinstein(-
Heimburg). Regenstein Castle (the line of Reinstein-Reinstein) was abandoned in the mid-15th century in favour of Blankenburg and
Derenburg. The last male descendant of the noble family, John Ernest, Count of Regenstein, died in 1599. Parts of the county evolved into the
Principality of Blankenburg. ==Seats==