Complex sentence: Some details of her life, including her following after the mid- 10th century, are not known for certain; the text documenting some of her most noteworthy accomplishments was most likely written after 1025.
Split into simpler sentences: Some details of her life, including her following after the mid-tenth century, is not known for certain. The text documenting some of her most noteworthy accomplishments was most likely written after 1025.