Detailed Instructions: This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.
Q: The Thuringian Realm existed until 531 and later, the Landgraviate of Thuringia was the largest state in the region, persisting between 1131 and 1247. Afterwards there was no state named Thuringia, nevertheless the term commonly described the region between the Harz mountains in the north, the Weiße Elster river in the east, the Franconian Forest in the south and the Werra river in the west. After the Treaty of Leipzig, Thuringia had its own dynasty again, the Ernestine Wettins. Their various lands formed the Free State of Thuringia, founded in 1920, together with some other small principalities. The Prussian territories around Erfurt, Mühlhausen and Nordhausen joined Thuringia in 1945.
A:
How long did the Thuringian realm exist?