There are 11 layers at Troy! Some are built during periods of development, others due to destruction.

Tin was imported from a lot of Europe, even from as far as Britain! Britain, Brittany (France), the Iberian Peninsula, Germany/CzechRepublic, and the Balkans all traded tin to the Mediterranean. Amber came from the Baltic region which is just as far! It's wild how far goods moved in the ancient world! (^(Tutankhamen's tomb has amber from the Baltics.))

What is less clear is the people side of all of it. We have some evidence for ships carrying trade goods, but it can be hard to assess if most of the trade was via direct, long distance trade relationships or was simply passed through many areas over time. (e.g. Changing hands 100 times from one place to the other) Most likely there was all of the above.