When Europeans first arrived on the Channel Islands in the 16th century, they encountered an ancient maritime society, the Chumash. Superbly adapted to island life, the Chumash harvested a wide range of resources, from fish, seals, sea lions, and shellfish, to acorns and other terrestrial foods. In sturdy plank canoes known as tomols, they fished deep water and regularly crossed to the mainland. There they developed extensive trading networks that reached into northern California and the deserts of the Southwest, often using shell beads for exchange.