Complex sentence: With the creation of the Soest district in 1817 its influence slowly rised again, however the industrialization of the Ruhr area did not reach Soest and thus it kept to be a small city.
Split into simpler sentences: With the creation of the Soest district in 1817 its influence slowly rose. However, the industrialization of the Ruhr area did not reach Soest, thus keeping it a small city.