Map of Schwarzburg in 1571, after the Treaty of Speyer (1570).<br>Until 1570, the four sons of count Günther XL ruled Schwarzburg together. Count William lobbied for a division of the county, and in December 1570 a preliminary division was agreed in Speyer.<br> The <i>Unterherrschaft</i> was divided between count William and John Günther I. The <i>Oberherrschaft</i> was ruled jointly by Günther XLI and Albrecht VII.
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<span class="int-own-work" lang="en">Own work</span><br>Based on Atlas des Saale- und mittleren Elbegebietes (Leipzig 1958), <a rel="nofollow" class="external autonumber" href="https://www.thueringen.de/imperia/md/content/staatsarchive/rudolstadt/karten/karten_schwarzburg-sondershausen_240412.pdf">[1]</a>, <a rel="nofollow" class="external autonumber" href="https://www.thueringen.de/imperia/md/content/staatsarchive/rudolstadt/karten/karten_schwarzburg-rudolstadt_240412.pdf">[2]</a> and Kurt Herrmann, <i>Die Erbteilungen im Hause Schwarzburg, Buchdruckerei Heinrich John</i> (Halle (Saale), 1919)