What is a large core area of Precambrian rocks called?

A large core area of Precambrian rocks is called a "craton." Cratons are stable continental crust that have survived the cycles of plate tectonics and tectonic activity for billions of years. They typically consist of ancient, igneous, and metamorphic rocks, forming the foundation of continents. Cratons are often divided into shields, which expose the ancient rocks at the surface, and platforms, which are covered by younger sedimentary layers.