What is largest natural region?

The tundra is the largest natural region on Earth, covering about one-fifth of the land surface. It is found in the northernmost regions of North America, Europe, and Asia, and is characterized by its cold, treeless climate and permafrost. The tundra is home to a variety of plant and animal life, including mosses, lichens, grasses, sedges, reindeer, caribou, wolves, and bears.