The Precambrian period lasted for almost 7/8ths of Earth's history. It spanned from about 4.5 billion years ago (the formation of the Earth) to about 541 million years ago.

This makes up the majority of Earth's history, with the remaining 1/8th being filled by the Phanerozoic eon, which includes all the familiar periods like the Paleozoic, Mesozoic, and Cenozoic.