sentences:  Throughout the 16th and 17th centuries successive Somali Sultans defied the Portuguese economic monopoly in the Indian Ocean by employing a new coinage which followed the Ottoman pattern, thus proclaiming an attitude of economic independence in regard to the Portuguese.In the mid-17th century, the Oromo Nation began expanding from its homeland around Lake Abaya in southern Ethiopia towards the southern Somali coast at the time when the Ajuran was at the height of its power.The Garen rulers conducted several military expeditions known as the "Gaal Madow" wars against the Oromo warriors, converting those that were captured to Islam.