Overview

The year 4 (written IV in Roman numerals) is recorded as the fourth year of the 1st century. In sources that use the Julian system it is described as a leap year that began on a Tuesday, while when projected backward into the modern Gregorian scheme the same year corresponds to a year beginning on Thursday. These differing weekday assignments reflect the chronological offset between the Julian calendar then in use and the later Gregorian calendar.

Calendar and dating conventions

People living at the time did not refer to the year as "AD 4." Instead, Romans identified years by the chief magistrates in office. Official records name the year as the Year of the Consulship of its two consuls. The use of the Anno Domini system — indicated here by Anno Domini — became common in medieval Europe only many centuries later; this system is one of several calendar era conventions historians use to label ancient years for modern readers across Europe and beyond.

Political and historical context

AD 4 falls within the early Roman Empire under the rule of Augustus, a period characterized by consolidation of imperial institutions and continued reliance on republican-era offices such as the consulship. Dating by consuls linked administrative records, legal documents and public inscriptions to a pair of named officials, a practice that helps historians anchor events in Roman chronology.

Notable characteristics

  • The year is part of the 1st century CE, an era of transition from Roman Republic institutions toward imperial administration.
  • Differences between Julian and proleptic Gregorian reckonings produce alternate weekday starts; this illustrates how calendar reforms affect retrospective dating.
  • Historical references to this year typically occur in Roman administrative lists, inscriptions and later chronological compilations.

Legacy and usage

Modern treatments of the year emphasize the mechanics of ancient dating and the relationship between contemporary record-keeping and later calendar systems. Scholars use cross-referencing of consul lists, astronomical data and surviving inscriptions to place events within the sequence of years historians now label as AD 1, AD 2, AD 3, AD 4 and so on. For general readers the year functions mainly as a temporal marker within the early imperial period rather than as a label tied to a single widely remembered event.

For further introductory material on calendars, Roman consular dating and the Anno Domini convention see related reference entries and guides: Year entry, Julian calendar, Gregorian calendar, and surveys of Roman government offices and chronology available through academic and public history resources.