Question - Why and how did the Byzantine Empire have so much influence on religion, culture, and trade in Russia and Eastern Europe?

Why and how did the Byzantine Empire have so much influence on religion, culture, and trade in Russia and Eastern Europe?

Answer:

Trade routes between Black Sea and the Baltic Sea, adoption of Orthodox Christianity by Russia and much of Eastern Europe, adoption of Greek alphabet for the Slavic languages by St. Cyril, and church architecture and religious art.