The crossword solution for the term 'Duchy Old German' is Saxe, which is a 4-letter word. Saxe is an area of Germany that was formerly a duchy, and it is located in the modern-day state of Saxony. The duchy was established in the 10th century and was ruled by the House of Wettin until 1918. It was one of the most powerful states in the Holy Roman Empire and was a major cultural center in Europe during the Middle Ages.