What is "speyergau"

Speyergau was a medieval county in the stem duchy of Franconia around the administrative centre of Speyer, Germany. It roughly covered the former Roman administrative area of Civitas Nemetum which is now the south-eastern portion of the Palatinate between Rhine and Palatinate Forest and some parts of northern Alsace. Much of it made up the major possession of the Salian dynasty of German kings.