The Indus Valley Civilisation starts around 3300 BC with what is referred to as the Early Harappan Phase (3300 to 2600 BC). The earliest examples of the Indus Script date to this period, as well as the emergence of citadels representing centralised authority and an increasingly urban quality of life. Trade networks linked this culture with related regional cultures and distant sources of raw materials, including lapis lazuli and other materials for bead-making. By this time, villagers had domesticated numerous crops, including peas, sesame seeds, dates, and cotton, as well as animals, including the water buffalo.