At around the same time, very late Precambrian, the Baikalian Orogeny (named for Lake Baikal, in southern Siberia) added some small continental blocks and island arc terranes to the southern margin of Siberia – which was not at the time connected to the Baltic Shield and Europe. That’s a much later assembly, marked by the Ural Mountaina.
Most of the Baikalian “events” spanned at least 150 million years, and were largely accomplished by the time the Cambrian opened. They set the scene, provide the geography, for not just the Cambrian, but for a good bit of Paleozoic time that we’ll be discussing over the coming months.
—Richard I. Gibson