Complex sentence: The treaty provided for a much smaller reservation, and provided that whites were not allowed to encroach on the reservation, and to further reduce the land would require an approval of three-fourths of the tribal members.
Split into simpler sentences: The treaty provided for a much smaller reservation, and stipulated that whites were not allowed to encroach on the reservation. Also, to further reduce the reserve's land would require an approval of three-fourths of the tribal members.