Work on the crossing of the Thuringian Forest and the closing of the gap between Plaue and Ritschenhausen was started in 1879 by the Prussian state railways.

The line quickly developed into a major north–south link, so that duplication between Neudietendorf and Grimmenthal was carried out between 1886 and 1893.

After the Second World War, the connection towards Bavaria was interrupted by the border between the American and Soviet occupation zones.

In 1984, the Neudietendorf–Arnstadt section was electrified, because there was insufficient capacity available in Erfurt Hauptbahnhof for the nightly changes of locomotives of the Städteexpress ("city express") service from Meiningen to Berlin, as well as the adding of extra passenger coaches and freight wagons.

It included, inter alia, the renovation of the Brandleite Tunnel, which had to be closed for nearly a year, and the installation of electronic interlocking in Arnstadt, which monitors the Neudietendorf–Rentwertshausen stretch.

Despite some operational problems, such as slopes with a maximum grade of 2.38% in the Thuringian forest and the need to reverse trains running to Würzburg in Schweinfurt, the line was a major long-distance north–south link until 1945.

A fast train operated in the early 1890s from Berlin to Stuttgart via Erfurt, Meiningen and Schweinfurt.

Express trains ran to Berlin, Dresden, Görlitz, Leipzig, Halle and Stralsund.

In 1981, there were eight pairs of trains, including the Städteexpress, Rennsteig (named after a crest in the Thuringian Forest) and the Städteschnellverkehr (“city rapid”) service to Berlin.

They were typically hauled by class 44 locomotives, using pulverised coal to avoid smoke while passing through the Brandleite Tunnel.