643 BC

643 BC was a year in the pre-Julian Roman calendar. As the Julian calendar was not established until 45 BC, this year is a proleptic date. Events and details provided for this year are based on retrospective reconstruction and historical records that are often fragmentary and subject to interpretation.

In terms of chronological notation, 643 BC falls within the 7th century BC. Determining the exact correlation between calendars of different cultures and eras requires complex calculations and assumptions, leading to inherent uncertainties. Historical accounts relating to this period should be approached with the understanding that precise dating is often impossible. The dating often relies upon archaeological discoveries, synchronisms with better-documented civilizations (such as Egypt or Assyria), and literary sources of varying reliability.