On December 14, 1819, Alabama was admitted to the Union as the 22nd state. As far back as 8,000 years ago, American Indian groups lived in the area that is now Alabama. Much later, Cherokee, Creek, Choctaw, and Chickasaw Indians moved into the region. After white settlers arrived in the area, they referred to these Indians as the “Civilized Tribes,” as they adopted many European customs. The Spanish explorer Alonso Álvarez de Piñeda reached Mobile Bay in 1519. Hernando de Soto, also a Spaniard, led an expedition into Alabama in 1540, making him the first European to explore the interior of the region. In 1559, Tristán de Luna ventured into Alabama searching for gold. He organized settlements around Mobile Bay and near today’s Claiborne, but these were soon abandoned after De Luna was relieved of his command and had to return to Mexico.