The fundamental problem of chronology is to synchronize events. By synchronizing an event it becomes possible to relate it to the current time and to compare the event to other events. Among historians, a typical need is to synchronize the reigns of kings and leaders in order to relate the history of one country or region to that of another. For example, the Chronicon of Eusebius (325 A.D.) is one of the major works of historical synchronism. This work has two sections. The first contains narrative chronicles of nine different kingdoms: Chaldean, Assyrian, Median, Lydian, Persian, Hebrew, Greek, Peloponnesian, Asian, and Roman. The second part is a long table synchronizing the events from each of the nine kingdoms in parallel columns.