... was the only significant imperial power in the Northern half of Africa at the end of the 18th century

Ottoman Turkey was the only significant imperial power in the Northern half of Africa at the end of the 18th century. The Ottoman Empire was a major political and military power in the world during this time, and its reach extended into North Africa. The Ottomans controlled a large portion of the region, including modern-day Libya, Tunisia, Algeria, and Morocco. This control allowed them to exert significant influence over the region and its peoples, and to shape its political and cultural landscape. At the end of the 18th century, the Ottoman Empire was the only significant imperial power in the Northern half of Africa, as the Portuguese Empire was primarily focused on West Africa and the Italo-Egyptian Empire did not yet exist.