Definition: Rewrite each original sentence in order to make it easier to understand by non-native speakers of English. You can do so by replacing complex words with simpler synonyms (i.e. paraphrasing), deleting unimportant information (i.e. compression), and/or splitting a long complex sentence into several simpler ones. The final simplified sentences need to be grammatical, fluent, and retain the main ideas of their original counterparts without altering their meanings.
Input: This was followed by the establishment of the Grey League (Grauer Bund), sometimes called Oberbund, in 1395 in the Upper Rhine valley.

In 1395 this was followed by the start of the Grey League or Oberbund  in Upper Rhine valley.