Complex sentence: The Point Peninsula Complex was a Native American culture located in Ontario and New York from 300 BCE to 700 CE (during the Middle Woodland period), and are thought to have been influenced by the Hopewell traditions of the Ohio River valley.
Split into simpler sentences: The Point Peninsula Complex was an indigenous culture located in Ontario and New York from 300 BCE to 700 CE (during the Middle Woodland period). The people are thought to have been influenced by the Hopewell traditions of the Ohio River valley.