Kassite Babylonian material dating back to the second millennium BC found in Al Khor Islands attests to trade relations between the inhabitants of Qatar and the Kassites in modern-day Bahrain. Among the findings were 3,000,000 crushed snail shells and Kassite potsherds. It has been suggested that Qatar is the earliest known site of shellfish dye production, owing to a Kassite purple dye industry which existed on the coast.