Complex sentence: In the late 17th century Chief Wyandanch gave much of the South Fork of Long Island to Lion Gardiner, although the tribe remained in the area until the Montauk peninsula was purchased by Arthur Bensen in 1879.
Split into simpler sentences: In the late 17th century Chief Wyandanch gave much of the South Fork of Long Island to Lion Gardiner. The remaining Montauk were still living in the area until the Montauk peninsula was purchased by Arthur Bensen in 1879.