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: Like most other regions of central and southern Germany, Thuringia has a significant industrial sector reaching back to the mid-19th-century industrialisation. The economic transition after the German reunification in 1990 led to the closure of most large-scale factories and companies, leaving small and medium-sized ones to dominate the manufacturing sector. Well-known industrial centres are Jena (a world centre for optical instruments with companies like Carl Zeiss, Schott and Jenoptik) and Eisenach, where BMW started its car production in the 1920s and an Opel factory is based today. The most important industrial branches today are engineering and metalworking, vehicle production and food industries. Especially the small and mid-sized towns in central and southwestern Thuringia (e.g. Arnstadt, Schmalkalden and Ohrdruf) are highly industrialised, whereas there are fewer industrial companies in the northern and eastern parts of the Land. Traditional industries like production of glass, porcelain and toys collapsed during the economic crises between 1930 and 1990.
A:
How far back does Thuringia's industrial sector go back?