The way in which plants and animals are distributed in the world results from a combination of factors. These include soil, climate and past history. Since life first began, the surface of the earth has undergone immense changes. Until perhaps 200–500 million years B.P.,* the continents were probably grouped close together, with an ice-cap at times covering parts of Africa and much of South America, India and Australia. Since then, they have drifted apart, India moving thousands of miles to the north-east until it collided with Asia. The separation of the continents isolated large groups of animals and is responsible for many of the peculiarities of the faunas of different regions of the world.