There are two explanations for the origin of the name "Chaîne de l'Épine". One traces "l'Épine" as a reference to a thorn from Christ's crown of thorns that Guillaume de Montbel brought back with him on his return from the Seventh Crusade in 1254. Montbel built the Château de l'Épine on the ridge above Nances and placed the holy thorn relic in the castle's chapel. In time, the chapel became such an important pilgrimage site that the name "l'Épine" was given to the whole mountain. The second explanation sees the Celtic god "Pen" as the source for both the name of the Chaîne de l'Épine ridge and the commune of Lépin-le-Lac to its west.