The first inhabitants of North America migrated from Siberia by way of the Bering land bridge and arrived at least 15,000 years ago, though increasing evidence suggests an even earlier arrival. After crossing the land bridge, the first Americans moved southward, either along the Pacific coast or through an interior ice-free corridor between the Cordilleran and Laurentide ice sheets. The Clovis culture appeared around 11,000 BC, and it is considered to be an ancestor of most of the later indigenous cultures of the Americas. While the Clovis culture was thought, throughout the late 20th century, to represent the first human settlement of the Americas, in recent years consensus has changed in recognition of pre-Clovis cultures. Over time, indigenous cultures in North America grew increasingly complex, and some, such as the pre-Columbian Mississippian culture in the southeast, developed advanced agriculture, grand architecture, and state-level societies. From approximately 800 to 1600 AD the Mississippian culture flourished, and its largest city Cahokia is considered the largest, most complex pre-Columbian archaeological site in the modern-day United States. In the southern Great Lakes region, the Iroquois Confederacy (Haudenosaunee) was established at some point between the twelfth and fifteenth centuries, lasting until the end of the Revolutionary War. The date of the first settlements of the Hawaiian Islands is a topic of continuing debate. Archaeological evidence seems to indicate a settlement as early as 124 AD. During his third and final voyage, Captain James Cook became the first European to begin formal contact with Hawaii. After his initial landfall in January 1778 at Waimea harbour, Kauai, Cook named the archipelago the "Sandwich Islands" after the fourth Earl of Sandwich—the acting First Lord of the Admiralty of the British Royal Navy.