Sandwiched between the earliest settlement of Eridu and the later "classical" Ubaid style, the culture is found as far north as Ras Al-Amiya. The Hadji Muhammed period saw the development of extensive canal networks from major settlements.[2] Irrigation agriculture, which seems to have developed first at Choga Mami (4700–4600 BC) and rapidly spread elsewhere, from the first required collective effort and centralised coordination of labour.