|4.5<ref name="OxfordArea">{{Cite book|last1=BangScheidel|first1=Peter Fibiger|url=https://books.google.com/books?id=9mkLEAAAQBAJ&pg=PA92Walter|title=The Oxford World History of Empire: Volume One: The Imperial Experience|last2=Bayly|first2=C. A.|last3=Scheidel|first3=Walter|date=2020-12-02|publisher=Oxford University Press|year=2020|isbn=978-0-19-977311-4|editor-last=Bang|editor-first=Peter Fibiger|editor-link=Peter Fibiger Bang|location=|pages=92–94|language=en|chapter=The Scale of Empire: Territory, Population, Distribution|author-link=Walter Scheidel|editor-last2=Bayly|editor-first2=C. A.|editor-link2=Christopher Bayly|editor-last3=Scheidel|editor-first3=Walter|editor-link3=Walter Scheidel|chapter-url=https://books.google.com/books?id=9mkLEAAAQBAJ&pg=PA92}}</ref>