Though they are not as well known as tribes like the Sioux or Cherokee, the Creek are one of the oldest and most important Native American tribes in North America. With roots that tie them to the Ancient Moundbuilders, the Creek were one of the most established groups in the Southeastern United States, and came to be known as one of the Five Civilized Tribes. It's also believed that the Creek were the first natives encountered by Spanish explorer Hernando De Soto's historic expedition in the mid-16th century. The Creek became known as one of the Five Civilized Tribes for quickly assimilating aspects of European culture, but in response to early European contact, the Muscogee established one of the strongest confederacies in the region. Despite becoming a dominant regional force, however, infighting brought about civil war in the early 19th century, and they were quickly wrapped up in the War of 1812 as well. By the end of that fighting, the Creek were compelled to cede millions of acres of land to the expanding United States, ushering in a new era that found the Creek occupying only a small strip of Alabama by the 1830s.