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: Baduhennna is solely attested by Tacitus' Annals where Tacitus records that a grove in Frisia was dedicated to her, and that near this grove 900 Roman prisoners were killed in 28 CE.

In Tacitus it is said that 900 soldiers were killed near a grove in Frisia that was dedicated to Baduhenna.