Named for the three rivers that water it:
黑龙江 (the Amur),
松花江 (the Songhua), and
乌苏里江 (the Ussuri). Once a vast marshland known as the
北大荒 ('Great Northern Wilderness'), it was reclaimed for agriculture from the 1950s onward and is now a major rice and soybean producer; surviving wetlands are protected as Ramsar sites.
