Isenburg-Grenzau was the name of several states of the Holy Roman Empire, based around the Lordship of Grenzau, in modern Rhineland-Palatinate, Germany. The first state called Isenburg-Grenzau existed 1158–1290; the second 1341–1439; and the third 1502–1664.
Read more about Isenburg-Grenzau: Isenburg-Grenzau (1158–1290), Isenburg-Grenzau (1341–1439), Isenburg-Grenzau (1502–1664)