The Permian is a geologic period and system characterized by widespread, diverse and maturing lifeforms which comes just after the Carboniferous and that extends from 299.0 ± 0.8 to 251.0 ± 0.4 Ma (million years before the present). It is the last period of the Paleozoic Era and famous for its' ending epoch event, the largest mass extinction known to science. The Permian period was named after the kingdom of Permia in modern-day Russia by Scottish geologist Roderick Murchison in 1841 (not the city of Perm, as commonly misconstrued).
Sea levels in the Permian remained generally low, and near-shore environments were limited by the collection of almost all major landmasses into a single continent -- Pangaea. One continent, even a very large one, has a smaller shoreline than six to eight smaller ones with the same total area. This could have in part caused the widespread extinctions of marine species at the end of the period by severely reducing shallow coastal areas preferred by many marine organisms.