From about 1130, their descendants called themselves after their family seat, Bilstein Castle, in the Höllental valley west of Albungen, today a village in the borough of Eschwege. This castle had probably been built by them around 1100. In this period they came into military conflict with the counts of Northeim, who around 1105/1110 had defeated Count Rugger I of Bilstein and destroyed the first, still weakly fortified Bielstein Castle. His successor, Rugger II of Bilstein, asserted himself with the construction of the new Bilstein Castle and began to develop the land around the castle, the woods on the Hoher Meißner, as, as "clearing demesne. For this purpose he also founded Germerode Abbey, which became the family abbey of the dynasty. The descriptive family name, the Bilsteiners, was later appended even to the early members of the house.
Burgraves
In the 12th century, the Ludovingians needed to place all responsibility for the management of the castle of Wartburg, particularly its security and the improvement of the fortifications, into the hands of an authorised representative. This person held the office of Burgrave of the Wartburg. With the appointment of the counts of Wartburg, who appear at the same time in the 13th century as the burgraves of Brandenburg at the neighbouring Brandenburg Castle, a side line of the counts of Bilstein were elevated to high status, although they were not related by blood to the Ludowingian family.
Decline and end
In 1301, Count Otto II of Bilstein, with the consent of his wife, Catharina, sold the Bilstein fief and subsequently also his allodial estate to Landgrave Henry I of Hesse. With his death in 1306 the comital line came to an end.
Links to other aristocratic families
There is evidence that the counts of Bilstein were related to the lords of Bilstein in Westphalia. According to the Reinhardsbrunn Chronicle by monk, Johannes Caput, from Ilfeld Abbey an Elger of Bilstein on the Werra built the Ilburg and called himself the Count of Ilfeld. In 1162 a nobleman of Ilfeld married Lutrude of Hohnstein and called himself thereafter Ilfeld-Hohnstein and, from 1182, just von Hohnstein.
Rugger II, Count of Bilstein, founded Germerode Abbey
Otto II of Bilstein was the last male member of the family line. In 1301 he sold the Bilstein fief and, subsequently, also his allodial estate to Landgrave Henry I of Hesse and died in 1306.