Complex sentence: After the Thirty Years' War, Most lost much of its economical and political significance, and it was not until the second half of the 19th century that the emergence of industry and mining brought renewed importance to the city.
Split into simpler sentences: After the Thirty Years' War, the city lost much of its economical and political significance. It was not until the second half of the 19th century that the emergence of industry and mining brought renewed importance to the city.