steppes
The most usual term for large, flat areas is plains.
Tundra is a nearly flat, treeless plain in the Arctic regions of Europe, North America and Asia
plains
savannahs
maria
Abyssal Plain. :)
Europe is a huge place (a continent) it contains areas with flat planes, others below sea level as well as areas of hills and mountains (the Alps).
Eastern Europe is mainly flat with some hills, although there are a few large mountain chains.
a large area of flat unforested grassland in southeastern Europe or Siberia.
a map of world is that in which all the countries are shown on a flat surface
They are call Maria ( Latin for "seas" ).
A plain is basically a large, flat area and flood plains are the large flat areas to either sides of rivers. These areas, when it rains so much that the river bursts its banks, are covered in water: flooded.