The first settlers to arrive at Mochlos did so in two waves. The very first settlers were colonists from Melos who arrived right at the beginning of the Bronze Age when EM I pottery was in production. They were obsidian blade workers who imported their raw material with them, produced blades at Mochlos and distributed them to other parts of Crete. The Greek-American excavation uncovered the remains of their occupation in 1989 and again in 2010 in the northwest part of the island. A second wave of settlers appear to have arrived later, during the time that EM IB pottery was being produced at Knossos. Seager reported remains of their settlement along the south coast and western terrace of the island, and the current excavations have uncovered four or five additional houses and half a dozen additional tombs belonging to this settlement. At the start the settlement was apparently small, like others established in eastern Crete at this time, but by the the second phase of the Prepalatial period (EM II), the settlement had expanded considerably, perhaps partly because of a larger migration of settlers into eastern Crete that led to the establishment of many new settlements. The settlers are thought to have come from central Crete and may have been prompted to move eastwards as a result of overcrowding in that part of Crete or as a result of conflict between the different cultures in the northern and southern part of the island. Mochlos offered several attractions to these settlers, chief of which were the natural harbor formed by its isthmus and the rich agricultural plain that lay across from the island on Crete. Through the EM II and III phases of the Prepalatial period, a period of 600 to 800 years, Mochlos flourished as a major center of population in Crete. Many scholars have stressed its importance during these formative years of Minoan civilization, and Mochlos has become a model site for the study of the cultural processes involved in the emergence of civilization. The island was a center for new industries, such as the manufacture of gold jewelry, stone vases and faience; it was an important trading center, sending its ships to Melos to bring back huge quantities of obsidian, and perhaps serving as a gateway for goods coming to Crete from the Near East; it is also one of the few sites of the period to show convincing evidence for a hierarchical social structure.