Final answer:
The Patriots faced setbacks in the west due to British restrictions on settlement beyond the Appalachian Mountains during the American Revolution.
Step-by-step explanation:
The setbacks that the Patriots faced in the west during the American Revolution were primarily due to the British government's restriction on settlement beyond the Appalachian Mountains. The British viewed westward expansion as a threat to their control and wanted to avoid conflicts with Native American tribes in the Ohio Valley. The Proclamation of 1763, which established a western boundary to the colonies, prohibited colonists from settling in the desired western lands, leading to disappointment and anger among the colonists.