The Ethiopian Highlands is a rugged mass of mountains in Ethiopia in Northeast Africa. It forms the largest continuous area of its elevation in the continent, with little of its surface falling below , while the summits reach heights of up to . It is sometimes called the Roof of Africa due to its height and large area. Most of the Ethiopian Highlands are part of central and northern Ethiopia, and its northernmost portion reaches into Eritrea. History In the southern parts of the Ethiopian Highlands once was located the Kingdom of Kaffa, a medieval early modern state, whence the coffee plant was exported to the Arabian Peninsula. The land of the former kingdom is mountainous with stretches of forest. The land is very fertile, capable of three harvests a year. The term coffee derives from the () and is traced to Kaffa. Physical geography The Highlands are divided into northwestern and southeastern portions by the Main Ethiopian Rift, which contains a number of salt lakes. The northwestern portion, known as the Abyssinian Massif, covers the Tigray and Amhara Regions, and includes the Semien Mountains, part of which has been designated the Simien Mountains National Park. Its summit, Ras Dashen (4,550 m), is the highest peak in Ethiopia. Lake Tana, the source of the Blue Nile, also lies in the northwestern portion of the Ethiopian Highlands. The southeastern portion is known as the Harar Massif. Its highest peaks are located in the Bale Zone of Ethiopia's Oromia Region. The Bale Mountains, also designated a national park, are nearly as high as those of Semien. The range includes peaks of over 4,000 m. Among these are Mount Tullu Demtu (4,337 m), which is the second-highest major independent mountain in Ethiopia, and Mount Batu (4,307 m). Most of the country's major cities are located at elevations of around above sea level, including Addis Ababa, Ethiopia's capital and largest city, and historic capitals such as Gondar and Axum. Geology The Ethiopian Highlands began to rise 75 million years ago, as magma from the Earth's mantle uplifted a broad dome of the ancient rocks of the Arabian-Nubian Shield. The opening of the Great Rift Valley split the dome of the Ethiopian Highlands into three parts; the mountains of the southern Arabian Peninsula are geologically part of the ancient Ethiopian Highlands, separated by the rifting which created the Red Sea and Gulf of Aden and