The show re-unites two old friends who were brought up in Karlsbad in the old Sudetenland, studied at the Prague Academy and shared a studio in the city, then moved to Liboc in the Czech countryside. Klemm saw the work of Emil Orlik in Vienna after Orlik's return from Japan and showed Thiemann how to make colour woodcuts. They published their first prints in a portfolio they called Alt-Prag about 1905 and, all in all, this is a chance to see the way young artists commonly worked together during this important period. There is an informative preview (in German) at http://www.kunstmarkt.com/pagesmag/kunst/_id360206-/news_detail.html .
Just how much they had in common they had at the time may be judged by two of the woodcuts here. The third one is Klemm's Moorbach from 1908, the year they both began to work at the artist's colony in Dachau. (The other two landscapes are by Thiemann, including a version of his Kiefern am Grunewaldsee). The exhibition takes their Dachau as its central subject. Klemm left Dachau for a post in Weimar in 1913 and eventually stopped making colour prints. Thiemann stayed for the rest of his life. The photograph below, taken in 1906, shows the two friends, with Thiemann on the left.
Many thanks to Klaus for letting me know about this exhibition. Other details can be found on the Dachau museums and galleries website.