Nefertiti bust (detail), Egyptian, 1345 BCE
Different cultures move out of the prehistoric era and into the historic era at different times. For example, the Great Pyramids at Giza in Egypt (historic) were being built at roughly the same time as Stonehenge in Great Britain (prehistoric).
Historic cultures are characterized by written language, specialized labor, agriculture and the domestication of animals, formation of cities, and metalworking. Metalworking will have a huge impact on the art made at this time, allowing both works made of metal and works created by use of metal tools. The first historic cultures will form around sources of fresh water. Mesopotamia developed between the Tigris and Euphrates rivers, and Egypt developed around the Nile River.
Ancient Mesopotamia:
Khan Academy: The cradle of civilization (reading)
Khan Academy: Sumerian art, an introduction (reading)
Khan Academy: Standing Male Worshipper from Tel Asmar (video - 4:48)
Khan Academy: Art of Akkad, an introduction (reading)
Khan Academy: Hammurabi (reading)
Khan Academy: Law Code of Hammurabi (video - 3:17)
Here's a goofy music video that nicely summarizes the Sumerians, Akkadians, and Babylonians: Ancient Mesopotamia Song (video - 3:51)
Ancient Egypt:
Khan Academy: Ancient Egypt, an introduction (read sections "Longevity" and "Consistency and Stability")
Khan Academy: Egyptian Art (reading)
Khan Academy: Materials & Techniques (reading)
Khan Academy: Akhenaten, Nefertiti, and Three Daughters (video - 5:03)
Khan Academy: Thutmose, Bust of Nefertiti (video - 4:01)
Egyptian mummy portraits (reading)