Complex sentence: The history of New York begins around 10,000 BC, when the first black peoples arrived By AD 1100, New York's main native cultures, the Iroquoian and Algonquian, had developed.
Split into simpler sentences: The history of New York begins around 10,000 BC, when the first black peoples arrived. By 1100 AD, New York's main native cultures, the Iroquoian and Algonquian, had developed.