The typical approach to direct contact is to look for the signs of the people making the journey (genetic, linguistic, and cultural transmission). If you don't

The typical approach to direct contact is to look for the signs of the people making the journey (genetic, linguistic, and cultural transmission). If you don't have these, they're often practically indistinguishable because the archaeological record inherently tends to be spotty, without continuous data points for uncommon trade goods. Moreover, the Asian northeast is vast and only lightly surveyed.