Mali's borders were created in 1960 from the division of colonial French West Africa. The country encompasses two geographically distinct regions. These two regions -- defined by the fertile, densely populated southern savannas and the arid, sparse northern Sahara -- are largely separated by the Niger River, which also serves as the historic lifeline of Malian commerce. These regions have independent geopolitical cores. The southern core is the Bambara agricultural triangle that includes Bamako -- the nation's capital. It's home to the Bambara people who share ethnic ties with Mali's southern neighbors: Burkina Faso, Ivory Coast, Guinea and Senegal. The northern core is found at the southern end of the Hoggar Mountains and is home to the nomadic Tuareg -- a Berber people with ties to populations in Niger, Mauritania and Algeria. Projecting political authority over both distinct regions is Mali's primary geographic challenge. The two largest cities in the north -- Timbuktu and Gao -- are on the Niger River and once served as major trading outposts between the two cores. Over the centuries, the establishment of sea routes by Europeans lessened the role of the Tuareg and these cities. Subsequently, the Tuareg Islamic sphere of influence has diminished, and the Saharan trade routes that once transferred salt, gold, ivory and slaves deteriorated. Today, Mali is one of the world's poorest countries. Its economy is based on agriculture, particularly cotton, livestock and gold mining. As the country's 2012 coup demonstrates, Bamako faces considerable challenges projecting domestic power from the extreme southwest of the country into the vast stretches of Mali's Saharan desert.