Qataris were engaged in the trading of pearls and date palms during this era. It has been argued that the remains of Dilmun settlements found in Qatar do not represent major evidence of long-term human habitation. Qatar remained largely uninhabited during this period due to regular migration by nomadic Arab tribes searching for untapped sources food and water. The settlements dating to the Dilmun period, particularly in Al Khor Island, may have been established to expedite trade journeys between Bahrain to the closest significant settlement in the Persian Gulf, Tell Abraq. Another scenario entails that the encampments were created by visiting fishermen or pearl fishers from Dilmun. It has also been suggested that the presence of pottery is indicative of trade between the inhabitants of Qatar and the Dilmun civilization, though this is considered unlikely due to the scarce population of the peninsula during this period. Kassite Babylonian-influenced materials dating back to the second millennium BC, which were found in Al Khor Island, reveal evidence of trade relations between the inhabitants of Qatar and the Kassite. Among the findings were 3,000,000 crushed snail shells and Kassite potsherds. It has been asserted that Qatar was the site of the earliest known production of shellfish dye owing to a purple dye industry operated by the Kassite which existed on the island. The dye was obtained from the Murex snail and was known as "Tyrian purple". Dye production may have been supervised by the Irtaza the great in Bahrain with the purpose of exporting the dye to Mesopotamia. Antiquity Iron Age and Babylonian–Persian control (680–325 BC) Assyrian king Esarhaddon led a successful campaign against Bazu, an area which encompassed Dilmun and Qatar, in c. 680 BC. To date, no archaeological evidence of early Iron Age settlements have been discovered in the Peninsula. This is likely due to adverse climatic changes rendering Qatar less inhabitable during this period. In the 5th century BC, Greek historian Herodotus published the earliest known description of the population of Qatar, describing its inhabitants as 'sea-faring Canaanites'. Hellenistic period (325–250 BC) Around 325 BC, Alexander the Great sent his top admiral, Androsthenes of Thasos, to survey the entire Persian Gulf. The requested charts arrived shortly after Alexander died in 323. Seleucus I Nicator was awarded the eastern part of the Ancient Greek Empire after Alexander's death. Starting from 312, he expanded the Seleucid Empire eastward of Babylon, purportedly encompassing