Grid cells and place cells in the old brain mostly track the location of one thing: the body. They know where the body is in its current environment. The neocortex, on the other hand, has about 150,000 copies of this circuit, one per cortical column. Therefore, the neocortex tracks thousands of locations simultaneously. For example, each small patch of your skin and each small patch of your retina has its own reference frame in the neocortex. Your five fingertips touching a cup are like five rats exploring a box.
