It was present in Alaska at 11,500 years (Upward Sun River).

It was present in Alaska at 9,000 years (Trail Creek).

What happened between 9,000 years and the present — how and when Ancient Beringian ancestry was transformed by the demographic events of the subsequent millennia — is a question that the current evidence is only beginning to address.

Understanding the population history of the Americas requires understanding not just where people were and when, but how different founding lineages interacted, mixed, separated, and persisted or disappeared over the course of thousands of years of post-founding demographic change.

The Trail Creek tooth is one data point in that understanding — a small data point, physically speaking, but one with a specific content that is genuinely informative about a specific period and a specific place.