The most prominent member of the comital family was Rainald of Dassel, chancellor to Emperor Frederick Barbarossa and Archbishop of Cologne.
At the beginning of the 12th century, the county covered the forested region of the Upper Weser (roughly the area of the present-day Solling-Vogler Nature Park) and its eastern foreland as far as the Leine valley.
The Ludolfic line flourished in the south, around Nienover, and benefited after 1180 initially from the fall of Henry the Lion.
The counts of Dassel had not only to hold their own against their neighbouring counties, but also against the duchy of Brunswick-Lüneburg as well as the bishoprics of Mainz, Paderborn and Hildesheim.
Inheritance divisions saw the territorial fragmentation of the county of Dassel but its eventual demise was caused by a lack of heirs.
The last count of Dassel, Simon, from the Adolfic line, gradually sold all the remaining land around his family seat and thereby dissolved the county.
To the south these included the Reinhardswald in a coarse triangle between the Weser, Fulda confluence and Diemel; to the north along the Leine, as well as other places scattered along the Elbe and Ruhr.
One of the counts of Dassel's last displays of power in the mid-13th century took place much further south of the border, in an arc formed by Körbecke, Grebenstein, and Reinhardshagen.
The counts' eight-tine deer antler is also present in the coat of arms of Nienover, a rural housing estate in Bodenfelde.
At the time of the county of Dassel, Bodenfelde was the southwestern boundary on the Upper Weser and the counts set up a customs post there.
The extension of the county of Dassel southward during the Ludolfic period is visible today in the Schönhagen coat of arms, as well.
Nonetheless, the trades and agriculture was sufficient to sustain continual economic development of the region in the centuries following.
His domain eventually extended to the upper Weser and Diemel, to the Reinhardswald, and toward Thuringia, the result of diverse connections from service, fief and family.
His wealth allowed him to provide his son Rainald with a comprehensive education at the prestigious bishopric of Hildesheim.
Sophie, daughter of Ludolf I, married Bernhard II of Wölpe at the end of the 12th century and then lived in the Middle Weser region.
During his reign, the house of Dassel was invested with Nienover castle and its rights, as well as the adjacent land in Solling.