Someone on Facebook linked to this essay examining the history of the First Nations in the Toronto area. Suffice it to say it's long, and complex.
South-central Ontario has a complex history. There is evidence that people lived in the area 11,000 years ago, when downtown Toronto was under the water of Lake Iroquois, Davenport Road was the shoreline, and mammoths and mastodons were the game of choice. Between 7,000 and 2,000 years ago, the shoreline began to look like the one we know today, including the Scarborough Bluffs and the Toronto Islands. At some point, Aboriginal people began using the Toronto Passage – the Humber and Rouge rivers – as a shortcut between Lake Ontario and Georgian Bay. It was a vital link in the trade route that ran from the Gulf of Mexico to Lake Superior.
Between 600 and 1600 CE, corn, beans, squash, and sunflowers were introduced from the south, and Iroquoian villages began to take on their well-known appearance: multi-family longhouses, sometimes enclosed by palisades, surrounded by cultivated fields. During the 14th, 15th, and 16th centuries, some of these people moved north to amalgamate with the Huron (or Wendat) Confederacy – which was also an Iroquoian culture – around Georgian Bay and Lake Simcoe. Others moved northwest and west to form the Petun (or Tionnontate) society around the Nottawasaga highlands and the Neutral (or Atiouandaronk) society around the Niagara peninsula. This led to larger confederacies that were stronger in warfare. It might also have been a calculated move to secure greater access to waterways. As a result of the amalgamations, the Huron-Wendat moved south from their traditional lands, using the now uninhabited area around Toronto for hunting, fishing, and settlements.
Between 1634 and 1640, half the Aboriginal population around the Great Lakes died from European disease, which meant the society now calling themselves the Haudenosaunee (“people of the longhouse”) – who were called the Iroquois by the French – had to capture and adopt outsiders to replace their losses. Competition for European trade was also a factor in the Haudenosaunee decision to destroy, defeat, disperse, or absorb the Hurons and other Iroquoian peoples living around the Great Lakes, including the Petun, Erie, Tobacco, Neutral, and Susquehannock. Some Hurons fled eastward toward Quebec and created a new nation, called the Wyandot. Others sought assistance from the Three Fires Confederacy – the Odawa, Potowatomi, and Ojibwe, collectively known as the Anishinabek – who were Algonquian-speaking societies living farther north. However, the largest group of surviving Huron were adopted by the Haudenosaunee when the Haudenosaunee created the Five Nations Confederacy (which included the Seneca, Mohawk, Onondaga, Oneida, and Cayuga nations, later joined by the Tuscarora to create the Six Nations Confederacy). The Odawa halted Haudenosaunee expansion northwest, but with the Huron withdrawal, the Haudenosaunee controlled south-central Ontario. By 1650-1660, the area around Toronto – and as far away as Pennsylvania, the Ohio Valley, and the lower Michigan peninsula – was Haudenosaunee territory.