The Duchy—originally a County—of Jülich comprises a state within the Holy Roman Empire from the eleventh to the eighteenth centuries.

The duchy lies left of the Rhine river between the Electorate of Cologne in the east and the Duchy of Limburg in the west.

It had territories on both sides of the river Rur, around its capital Jülich – the former Roman Iuliacum – in the lower Rhineland.

The duchy amalgamates with the County of Berg beyond the Rhine in 1423, and from then on also beomes known as Jülich-Berg.Its territory lies in present-day Germany (part of North Rhine-Westphalia) and in the present-day Netherlands (part of the Limburg province), its population sharing the same Limburgish dialect.