Though "Assam" generally denotes the distinctive black teas from Assam, the region produces smaller quantities of green and white teas as well with their own distinctive characteristics.
Historically, Assam is the second commercial tea production region after southern China. Southern China and Assam are the only two regions in the world with native tea plants. Assam tea revolutionized tea drinking habits in the 19th century since the tea, produced from a different variety of the tea plant, yielded a different kind of tea. ( source wiki )