As the book was redacted by Judean writers, it is not unnatural that the summary notices of the kings of Judah are more elaborate than those of Israel. In the former case, but not in the latter, the age of the king at his accession and the name of his mother are mentioned. One curious feature of these notices is that the statement of a king's accession, whether in Israel or Judah, is always accompanied by a statement of the corresponding year in the contemporary reign of the sister kingdom. The notices conform to this type: "In the twenty and seventh year of Jeroboam, king of Israel, began Azariah, son of Amaziah, king of Judah, to reign," 2 Kings xv. 1. It is practically certain that these synchronisms, as they are called, are not contemporary but the work of the redactors. There is no reason to suppose that the kings of either country would have dated their own reigns with reference to the other; besides, the synchronisms do not strictly agree with the other chronological notices of the reigns. The period between the division of the kingdoms and the fall of Samaria is estimated as 260 years in the story of the kings of Judah, but only as 242 in the case of Israel. Probably the original documents contained the number of years in the reign, and the dates of the more important events; but the synchronisms represent an artificial scheme created by the redactor. Traces of such a system are present in 1 Kings vi. 1, according to which 480 years, i.e. twelve generations of forty years each, elapsed between the exodus and the building of the temple.