The Arabs understandably did everything they could to protect their monopoly. Coffee beans were treated before being shipped to ensure they were sterile and could not be used to seed new coffee plants; foreigners were excluded from coffee-producing areas. First to break the Arab monopoly were the Dutch, who displaced the Portuguese as the dominant European nation in the East Indies during the seventeenth century, gaining control of the spice trade in the process and briefly becoming the world's leading commercial power.