Approximately 13,000 years ago, the one-kilometre-thick glaciers of the last ice age melted northwards from southern Ontario, and in their wake, left behind large meltwater lakes. Geologists call one of those bodies of water – a kind of large version of Lake Ontario – ‘Lake Iroquois.' Its water level was 40 metres higher than today's lake, and thus its shoreline stood at the hill by Davenport Road (meaning that the present-day downtown was once underwater). Around 11,700 years ago, Lake Iroquois found a new outlet to the Atlantic Ocean – the St Lawrence – instead of its earlier Mohawk and Hudson river routes. That caused the lake to drain to a level 100 metres below that of today's Lake Ontario by roughly 11,400 years ago, and thus its shoreline stood far to the south of the modern one.
Around 10,500-11,000 years ago, a small number of people moved into the cold sub-arctic landscape of ancient Ontario from the south to pursue the big game animals that preceded them. With the shoreline of ancient Lake Ontario lying about 20 kilometres south of modern Toronto, many of the campsites of these people are now lost to archaeologists. Nevertheless, from other sites in Ontario, we know that these early inhabitants fished and gathered but relied mainly on hunting caribou, as well as mammoths, mastodons, and smaller animals, in a region consisting of tundra and boreal forest. During the course of each year, they travelled across large distance
By about 8,000 years ago, the climate had warmed to a point comparable to modern levels, which allowed for a new kind of temperate forest environment to evolve in southern Ontario. During this transition, much of the big game became extinct, the caribou drifted north, but white-tailed deer moved in to take their place. Another development that helped to define the Toronto area occurred between roughly 7,000 and 2,000 years ago: rising water levels in Lake Ontario and soil erosion from Scarborough Bluffs created the Toronto Islands, the harbour, and a mainland shoreline similar to the modern one.
At some point in the distant past, indigenous people discovered a convenient shortcut between Lake Ontario in the south and Georgian Bay in the north. Later known as the ‘Toronto Passage,' main branches of this route ran north from the Humber and Rouge rivers, across the Oak Ridges Moraine, into the Lake Simcoe drainage basin, and then to Georgian Bay, Lake Huron, and the world beyond.
People expanded the range of foodstuffs they used to support themselves as the climate and environment evolved, with fishing in particular growing in importance. Over the millennia, these indigenous societies grew in complexity. For instance, related families began to congregate in large spring and summer camps near the mouths of rivers to catch fish, trade, and engage in communal social and spiritual events around 3,000 years ago. Physically, the increasing cultural maturity was represented by the introduction of such technological innovations as pottery and bows and arrows. The population also rose through the centuries, to roughly 10,000 in southern Ontario by about 1,500 years ago, with possibly 500 people living along each of the major rivers in the Toronto area. The various communities seem to have shared ideas and cultural practices widely with other groups, indicating that they engaged in a significant degree of interaction across Ontario and beyond. We see this archaeologically, for instance, by similarities in many of the excavated sites across the lower Great Lakes and by the presence of trade goods from far away, such as copper mined from surface deposits near Lake Superior and marine shell objects from today's southern United States.
As part of the exchange of technologies and ideas in native North America, corn, beans, squash, sunflowers, and tobacco were introduced into Ontario from the south. Scholars are uncertain as to when corn arrived, but they favour a point roughly 1,400 years ago. They disagree on whether the important crops of beans and squash appeared at the same time as corn or if they came in subsequent centuries. They also do not agree on whether the horticultural societies that emerged in Ontario arose from within the existing, long-standing population, or consisted of other native people who moved here from the south, or were a mix of indigenous and immigrant groups. Nevertheless, they believe that crops became increasingly important in people's diets as the centuries passed. In the process, the move towards reliance on farming helped to shape the horticultural Iroquoian societies that developed about 1,100 years ago in the lower Great Lakes. (Iroquoians comprised people who belonged to the same language group, in contrast to the other main indigenous language group in the Great Lakes, the Algonkian.)
An important shift that came with the adaptation of horticulture was that people slowly abandoned much of the mobility that had characterized life in southern Ontario for thousands of years. In its place semi-permanent villages developed, from which people moved out during parts of the year to hunt, fish, gather, or otherwise meet their subsistence needs as supplements to the farming that lay at the heart of their work.
Iroquoian villages changed over time, and by a point about 700 years ago these communities reached their ‘classic' appearance, typically consisting of longhouses, sometimes surrounded by defensive stockades, overlooking cultivated fields. Often Iroquoian villages were located on higher, defensible ground, but nevertheless, access to waterways and wetlands was important in choosing settlement locations because of their place in supporting fishing, hunting, and gathering, as well as for travelling for trade, diplomatic, and military purposes. There were early versions of these Iroquoian villages in the Toronto region starting about 1,100 years ago, although perhaps the most famous community from an archaeological perspective was the 15th-century Parsons site south of York University. Yet, other sites exist to tell us about Iroquoian Toronto, such as the important 14th-century Alexandra site in Scarborough, discovered only in 2000.
Iroquoian villages typically lasted from 10 to 20 years before their inhabitants relocated to new sites when the longhouses deteriorated, the fields became sterile, and people had to walk longer distances for firewood and other necessities that previously had been found close to home. After being abandoned, the old stockades and longhouses could be taken apart for building materials and firewood but eventually the forest reclaimed the former village sites and the soil gradually regained its fertility. During that process, the old settlements served as meadowlands and thinly forested environments, which attracted deer and helped to sustain the animal population that people utilized for food, clothing, and other materials.
We do not know when the first European reached the Toronto area, although there is no question that it occurred in the 17th century. Earlier historians claimed that Étienne Brûlé, the protégé of Samuel de Champlain, travelled down the Toronto Passage from Huronia in 1615. However, later scholars believe that this view is incorrect. Brûlé had set out from Champlain's Quebec to go up the Ottawa River and across central Ontario to live with the Hurons near Georgian Bay as part of an early French effort to build alliances with the natives. Champlain also travelled to Huronia in 1615 by the Ottawa route and then participated in a campaign against the Hurons' Iroquois enemies in New York. Before setting off, Champlain let Brûlé join some Hurons on a journey south to recruit help from another aboriginal people at war with the Iroquois, the Susquehannocks of modern Pennsylvania. While earlier antiquarians thought that Brûlé came down the Toronto Passage, he likely travelled south on a more westerly route, not to Lake Ontario, but to Lake Erie, before crossing the Niagara River to continue southward. It made better sense for Brûlé to use a route to the west of Toronto to reduce the chances of being intercepted by Iroquois war parties and to work around the western boundaries of the Iroquois homelands in New York. (Champlain himself did not come near Toronto; instead, he travelled southeast from Huronia to the Bay of Quinte before crossing Lake Ontario to attack the Iroquois in 1615.)