Jens Olof Lasthein, a Swedish-born photographer brought up in Denmark, has spent much of his career travelling around the European hinterlands, where international boundaries have been shifting for centuries. His new book, Meanwhile Across the Mountain, published by Max Ström, is a stunning survey of the Caucasus – the part of southeastern Europe that used to belong to the Soviet Union, but is now a collection of sovereign states and breakaway regions such as South Ossetia, Dagestan and Chechnya.