Simplify the following text for a Grade 8 native English-speaking person.
Original: This act shocked the religious conscience of Mesopotamia ; the subsequent murder of Sennacherib by two of his sons was held to be in expiation of it , and his successor Esarhaddon hastened to rebuild the old city , to receive there his crown , and make it his residence during part of the year .
Simplified: This act shocked the religious conscience of Mesopotamia . After the murder of Sennacherib by two of his sons , his successor Esarhaddon hastened to rebuild the old city .