The Roman imperial period is the expansion of political and cultural influence of the Roman Empire. The period begins with the reign of Augustus (r. 27 BC – AD 14), and it is taken to end variously between the late 3rd and the late 4th century, with the beginning of late antiquity. Despite the end of the "Roman imperial period", the Roman Empire continued to exist under the rule of the Roman emperors into Late Antiquity and beyond, except in the Western Empire, over which the Romans' political and military control was lost in the course of the 5th-century fall of the Western Roman Empire.

This article needs attention from an expert in Rome. The specific problem is: Extremely incomplete and unbalanced presentation of historiography. (May 2023)

You can help expand this article with text translated from the corresponding article in German. (June 2022) Click [show] for important translation instructions. View a machine-translated version of the German article. Machine translation, like DeepL or Google Translate, is a useful starting point for translations, but translators must revise errors as necessary and confirm that the translation is accurate, rather than simply copy-pasting machine-translated text into the English Wikipedia. Consider adding a topic to this template: there are already 9,106 articles in the main category, and specifying|topic= will aid in categorization. Do not translate text that appears unreliable or low-quality. If possible, verify the text with references provided in the foreign-language article. You must provide copyright attribution in the edit summary accompanying your translation by providing an interlanguage link to the source of your translation. A model attribution edit summary is Content in this edit is translated from the existing German Wikipedia article at [[:de:Römische Kaiserzeit]]; see its history for attribution. You should also add the template {{Translated|de|Römische Kaiserzeit}} to the talk page. For more guidance, see Wikipedia:Translation.

In historiography, the "imperial period" is by convention taken to last from 27 BCE to CE 284. In archaeology, on the other hand, the term is usually taken to cover the period of c. CE 1 to 375 (the latter being a conventional date for the onset of the Migration Period). This follows Hans Jürgen Eggers [de] (1955), who used a periodization of "early imperial period" (German: frühkaiserzeitlich) B1 to B2 and "late imperial period" (German: spätkaiserzeitlich) C1 to C3, reflecting the history of Roman pottery imports to Magna Germania and other parts of Barbaricum (Eggers A corresponds to La Tène D). In the chronology of Eggers (1955):^[1]

The term "Roman imperial period" has been used as opposed to "late antiquity", i.e. implying the "early" and "middle" imperial period of the late 1st century BC to the 3rd century CE. The "Roman imperial period" in this sense would end with the reforms under Diocletian and the beginning of the Christianization of the Roman Empire. The period is roughly equivalent in span to the "Principate", the early period of Roman imperial rule from Augustus to Diocletian (r. 284–305), succeeded by the "Dominate".

• History of the Roman Empire
• List of Roman Emperors
• Roman Iron Age