Complex sentence: Fort Boise's initial location was on the Boise River about seven miles above its mouth, it was relocated in 1838 nearer the mouth at the Snake River, about five miles northwest of the present town of Parma, south of Nyssa, Oregon.
Split into simpler sentences: Fort Boise's initial location was on the Boise River about seven miles above its mouth. It was relocated in 1838 at the Boise River's mouth at the Snake River, about five miles northwest of the present town of Parma, south of Nyssa, Oregon.