That the Chinese used oil from natural seeps as fuel to boil salt brine into salt. Initially bamboo was pounded vertically into oil containing seeps and removed by suction. With time this led to drilling for oil, as they needed to penetrate deeper and deeper into oil containing underground seeps. In 347 AD oil wells were drilled in China up to 800 feet deep using bits attached to bamboo poles. Connecting lengths of bamboo to carry oil to their salt brine work sites; they were the first to invent an elementary oil pipeline.