Süd-Thüringen-Bahn GmbH (STB) was founded in December 1999 and the transport contract with the Free State of Thuringia was signed in February 2000.

It was originally planned - but not implemented - for STB to take over passenger transport on the Bad Salzungen–Vacha railway for the timetable change in 2001, since due to disputes between the Free State of Thuringia and the Wartburgkreis (parallel bus traffic) the local rail passenger transport (SPNV) was terminated there on 9 June 2001.

Since the Regio Shuttles are equipped with modern central buffer couplings, this so-called winging was possible at the push of a button.

The infrastructure company responsible for the Eisfeld-Sonneberg and Sonneberg-Lauscha-Neuhaus am Rennweg sections is not DB Netz AG, but the private Thüringer Eisenbahn GmbH (ThE), which leased these lines in August 2001 for 17 years and has comprehensively renovated them since then.

The STB was able to prevail against other applicants in the new tender for the routes in the "Dieselnetz Südthüringen"[4] and thus continues to operate its main network from December 2017 to 2028.

The contract was signed on 6 April 2016 in Meiningen by Thuringia's Transport Minister Birgit Keller and the STB managing directors Michael Hecht and Susanne Wenzel.

The division of the STB 44 and EB 46 lines at Plaue ceased in December 2017 and the journey time between Meiningen and Erfurt was shortened by 10 to 15 minutes.

The 37 shuttles, five of them from ODEG, were modernised and received an extensive redesign in conventional green and white before the contract change.