Complex sentence: Robin Smith was a British climbers of the pioneering 1950s and early 60s, who, fell to his death on a snow slope in the Pamirs on an Anglo-Soviet experdition at the age of 23.
Split into simpler sentences: Robin Smith was a British climber of the pioneering 1950s and early 60s. He fell to his death on a snow slope in the Pamirs, during an Anglo-Soviet expedition, at the age of 23.