Complex sentence: Banda was the world's only source of nutmeg and mace, spices used as flavourings, medicines, preserving agents, that were at the time highly valued in European markets; sold by Arab traders to the Venetians for exorbitant prices.
Split into simpler sentences: Banda was the world's only source of nutmeg and mace, spices used as flavourings, medicines, and preserving agents that were at the time highly valued in European markets. They were sold by Arab traders to the Venetians for exorbitant prices.