The town's first documentary mention came in 1159 in an "enfeoffment" document in which a nobleman named Siegfried von Runkel had his name appear as a witness. It is believed that this Siegfried was the one who built Runkel Castle. In 1191 Siegfried married a countess of Katzenelnbogen. This high noble family forced Dietrich of Runkel to open his castles Runkel and Dehrn. No later than 1230, the castle had a chapel, thereby giving Runkel its first church building. In 1288, after years of family disputes, the Lords of Runkel and those of Westerburg sundered into two lines. In 1440, building work began on the Lahn bridge, but owing to the rift between the Runkels and the Westerburgs, the work took until 1448. In 1447 Count Philipp of Katzenelnbogen was the liege lord.