Simplify the following text for a Grade 15 native English-speaking person.
Original: Although Septimius Severus successfully restored peace following the upheaval of the late 2nd century , the dynasty was disturbed by highly unstable family relationships , and constant political turmoil , foreshadowing the imminent Crisis of the Third Century .
Simplified: Although Septimius Severus successfully restored peace following the upheaval of the late 2nd century , the dynasty was disturbed by unstable family relationships , and constant political turmoil .