Sizzo also established Georgenthal Abbey and in 1157, he accompanied Emperor Frederick I Barbarossa during his campaign against High Duke Bolesław IV the Curly of Poland.

In 1197, Sizzo's grandson Henry II divided the common heritage with his brother Günther III and made Schwarzburg Castle his residence.

The Schwarzburg lands were again divided among his successors until in 1538 when Count Günther XL the Rich was able to unite the territories including Frankenhausen and Rudolstadt under his rule.

However, after his death in 1583, his younger brothers again divided the county: John Günther I received the territory around Arnstadt, later called Schwarzburg-Sondershausen, while Albrecht VII inherited the lands of Schwarzburg-Rudolstadt.

According to this alternative numbering, there's a different counting for Schwarzburg, Käfernburg (from 1223 onwards) and Hallermund (as an already existing county which came into the family by marriage).