Question

What region became a crossroads where farmers, traders, and invaders settled, traded, and exchange ideas

Answer 1

If more context is provided, I might be able to help further with this, but my mind immediately leaps to Constantinople as the answer to this question. Trade between the East and West of the Eurasian continent was more or less funneled through Constantinople for centuries due to the reliance of traders on land trade routes and the lack of any real viable sea-route to Asia.