A grain grater from La Tène times may well be evidence that Ernst was already settled by 250 BC, and that it is therefore of Celtic origin. Even the earliest documentary mention of Ernst as "Arnesche" shows the village's Celtic beginnings. In AD 670, “Hilduin” bequeathed vineyards in Ernst to his brother-in-law. Ernst was made up of two constituent centres then, Oberernst and Niederernst, but was always a unified municipality. In the Middle Ages, lower court jurisdiction was exercised through the Valwig-Ernst court. When Ernst passed along with the Rhineland to Prussia, the Prussian government decreed that Oberernst, where the parish church and the old town hall stood, and Niederernst were to grow together into one centre, a project that, as can be seen today, was at least successful on the road alongside the Moselle, if nowhere else.