Complex sentence: Besides the aboriginal people of Tasmania, the Andamanese were the only people who in the 19th century knew no method of making fire, carefully preserving embers in hollowed-out trees from fires caused by lightning strikes.
Split into simpler sentences: Besides the aboriginal people of Tasmania, the Andamanese were the only people who in the 19th century knew no method of making fire. They instead carefully preserved embers in hollowed-out trees from fires caused by lightning strikes.