The Ilsenburg Royal Hunting Palatinate was first mentioned in 995. On 7th July of that year Otto III issued a letter of safe conduct to the neighbouring Drübeck Monastery while staying at the “Elysynaburg” Royal Hunting Palatinate situated high above the River Ilse.
On 15th April 1003 King Heinrich II made a gift of his Hunting Palatinate, including appurtenances, to Halberstadt Church. Sometime between 1003 and 1018 Ilsenburg Abbey was founded here. Royal troops were ousted to the Ilsestein. As a consequence they fought the abbey throughout the 11th century.
In 1018 Bishop Arnolf endowed the new abbey with a charter, which could be regarded as a deed of foundation, granting land and tithe, and settled monks of the Benedictine Order there. Though the charter is a forgery, assumed to date from the 12th century, it was based on genuine sources. He first made a present of land to Ilsenburg, with appurtenances and usage, as he had received it from the King. According to the 1018 charter this included 68½ Hufen of land (Hufe = a mediaeval measure: 68½ Hufen = approximately 2,000 acres) as well as tithe in Bernardingerode, Südschauen, Berßel, Thiederzingerode, Dudingerode (wasteland settlement below Vienenburg), Wenderode near Vienenburg, Brodesende etc.
The bishop appointed Ezilo as first abbot, after which free elections for abbot took place at Ilsenburg.