Dozens of archaeological sites throughout Asia and Europe show how people migrated from Africa and settled these two continents during the last Ice Age (100,000 to 15,000 years ago).
Archaeological studies have also provided much information about the people who first arrived in the Americas over 12,000 years ago.
Archaeology became established as a formal discipline in the 19th and early 20th centuries.
Archaeology plays a major role in the study of early civilizations, such as those of the Sumerians of Mesopotamia, who built the city of Ur, and the ancient Egyptians, who are famous for the pyramids near the city of Giza and the royal sepulchers (tombs) of the Valley of the Kings at Thebes.
Other sites that represent great human achievement are as varied as the cliff dwellings of the ancient Anasazi (a group of early Native Americans) at Mesa Verde, Colorado (see Mesa Verde National Park); the Inca city of Machu Picchu high in the Andes Mountains of Peru; and the mysterious, massive stone portrait heads of remote Easter Island in the Pacific.
Many of the objects left behind by past human societies are not present in the archaeological record because they have disintegrated over time.
The material remains that still exist after hundreds, thousands, or millions of years have survived because of favorable preservation conditions in the soil or atmosphere.
Archaeological research spans the entire development of phenomena that are unique to humans.
For instance, archaeology tells the story of when people learned to bury their dead and developed beliefs in an afterlife.The earliest archaeological sites include those at Hadar, Ethiopia; Olduvai Gorge and Laetoli, Tanzania; East Turkana, Kenya; and elsewhere in East Africa.These sites contain evidence of the first appearance of bipedal (upright walking), apelike early humans.Today, archaeologists study the great cultural diversity of humanity in every corner of the world.Archaeological study covers an extremely long span of time and a great variety of subjects.Laetoli even reveals footprints of humans from 3.6 million years ago.