Complex sentence: The Seals also provide the Netsilik with fat to light their soapstone lamps which were used to heat their Igloos, this made the Netsilik one of the few peoples to hunt for their heating fuel.
Split into simpler sentences: The Seals also provide the Netsilik with fat for their soapstone lamps, which both lit and heated the Igloos. This made the Netsilik one of the few peoples to hunt for their heating fuel.