More than 5,000 years ago, groups of people in different parts of the world began to keep written records. The development and use of writing marked the beginning of recorded history. Humans and their ancestors, however, had lived on Earth for many tens of thousands of years before recorded history. The long period of time before people invented writing is called prehistory.
Studying ancient footprints is one way scientists can learn about the past. These footprints, preserved in volcanic ash, were made in Tanzania some 3.5 million years ago.
Most of the events you will read about here comes from the work of historians. Historians are experts in the study of how people lived in the historical past. Historians study artifacts, or objects made by humans. Clothing, coins, artwork, and grave sites are all types of artifacts.
However, historians rely even more on written evidence, such as letters or tax records. Historians of the recent past also study such evidence as photographs or films.
Sometimes historians have a wealth of written records. They can study diaries, official histories, birth and death records, and eyewitness accounts. At other times, they have relatively few records, or records that merely list a name or date.
Like a detective, a historian must evaluate all evidence to determine if it is reliable. Do records of an official meeting tell us exactly what was said? Who took notes? Was a letter writer really giving an eyewitness account or just passing on rumors? Is the letter a forgery? Historians try to find the answers to questions like these.