Researching Külz's history is not easy, as besides the three forms of the name already mentioned, the forms "Engeltroutkülz" and "Osterkülz" also crop up in documents. Furthermore, Alterkülz in the "Verbandsgemeinde" of Kastellaun is sometimes named as "In der Külze", "Auf der Külze" or "Külz". To make matters worse, the “Külz” mentioned in 1204, 1293 and 1294 in connection with the Cistercian convent of Chumbd (Kumbd) seems to have been, not today's Külz, but rather a now vanished village that lay on the upper reaches of the Osterkülz. Moreover, Neuerkirch once also bore the name Külz. Only when the church was built could a more exact name be applied to the village: Külz bei der Kirche (“Külz at the Church”).