Living in a concrete box with hot water pouring from the tap, a refrigerator cooling our food and wi-fi connecting us to the rest of the world, we can barely imagine a day in a life of, say, Tsaatan people. They move 5 to 10 times per year, building huts when the temperature is -40 and herding reindeer for transportation, clothing and food. “Before They Pass Away,” a long-term project by photographer Jimmy Nelson, gives us the unique opportunity to discover slowly vanishing tribes from all over the world.