The oldest human remains found in the Philippines date back 22,000 years ago. The first inhabitants were Negritos who arrived during the Old Stone Age by walking across land bridges. They were later joined by maritime Indonesians during the New Stone Age. Malays also immigrated and introduced festivals, codes of law, and contributed to Iron Age culture. Ancient Filipinos had developed music, architecture like native houses, and art forms including pottery, wood carvings, tattoos, and petroglyph cave paintings as early as 3000 BC.