Mali has always been known as the location of the Mali Empire and Timbuktu, the fabled city of learning. Timbuktu became a real center of the trans-Siberian trade due to trade in gold and salt which have taken place here. Starting with the 12th century, West African scholars gathered at the Sankore mosque to study the Koran, law, literature, and history. Timbuktu, like many other important Malian cities, is along the Niger River, which represents a thoroughfare for commerce and travelers. Malians also contributed to the culture and development of the United States of America.