Complex sentence: This legislation included the White Cloud and Boulder Mountains as part of the SNRA as well as the Sawtooth Primitive Area, which became the Sawtooth Wilderness, covering and part of the National Wilderness Preservation System under the Wilderness Act of 1964.
Split into simpler sentences: This legislation included the White Cloud and Boulder Mountains as part of the SNRA. The Sawtooth Primitive Area became the Sawtooth Wilderness (also in the SNRA) as part of the National Wilderness Preservation System under the Wilderness Act of 1964.