The Arab slave trade from East Africa predates European trans-Atlantic trade by 700 years, shipping 11- 18 million Africans across the Red Sea between 650 and 1900. There are also stories of a trail of tears lined with coffee trees leading through Kenya along the route where slavers took their human cargo. The berries may have been used, some think, to keep those half-starved captives conscious enough to complete their hellish journey. It is believed this was one of the ways coffee may have first crossed the Red Sea from Ethiopia to Yemen.
Coffee was first used in Sufi ceremonies in 15th century Yemen.
Sufism was a mystical branch of the Muslim religion that grew in popularity during the 16th century at a time when people were looking for meaning in a rapidly changing world. As coffee promoted wakefulness, it soon became established within the Sufi dakhr and quickly spread from Yemen to other parts of the Ottoman lands through well-established trade routes.
Even in pre-Islamic times trade routes criss-crossed the Arabian Penninsula. Sufis, who were merchants and traders, carried a supply of coffee with them and soon established coffee cultures whereever there were trading settlements.