Why did most Native Americans groups side with Britain?

Because they wanted to safeguard their tribal lands and hoped a British victory would relieve the unrelenting pressure.

Hope this Helped! :T

Explanation:

most Native American tribes during the War of 1812 sided with British because they wanted to safeguard their tribal lands, and hoped a British victory would relieve the unrelenting pressure they were experiencing from U.S. settlers who wanted to push further into Native American lands in southern Canada and in the lower Great Lakes and the south. Although some tribes remained neutral and some supported the United States, the majority allied with Britain.