Who was the first Roman emperor? What country had Andriantsimitoviaminandriana as its king? Who succeeded Harald Bluetooth? From Horus Aha, first king of Egypt, to Abd Allah II, present king of Jordan, this compact and useful reference book charts five millennia of kings, queens, emperors, empresses, regencies, joint reigns, abdications, depositions, interregna, foreign rule, mandates, protectorates, and dynastic unions.

Chronological tables show the names and dates of rulers and their family relationships, while supplementary notes cover problems of chronology, calendars and dating systems, margins of error for uncertain dates, and names and titles. Bibliographies document the research and guide the reader to additional information.