Complex sentence: In North America, spruce gum was chewed by Native Americans, and was later introduced to the early American pioneers and was sold commercially by the 19th century, by John B. Curtis amongst others.
Split into simpler sentences: In North America, it is known that spruce gum was chewed by Native Americans. Spruce gum was later introduced to the early American pioneers and was sold commercially by the 19th century, by John B. Curtis amongst others.