While droughts were not uncommon in the centuries of the first millennium AD, a population explosion occurred with the coming of the medieval warm period. "Marine productivity soared between 950 and 1300 as natural upwelling intensified off the coast." Before the mission period, the Chumash lived in over 150 independent villages, speaking variations of the same language. Much of their culture consisted of basketry, bead manufacturing and trading, cuisine of local abalone and clam, herbalism which consisted of using local herbs to produce teas and medical reliefs, rock art, and the scorpion tree. The scorpion tree was significant to the Chumash as shown in its arborglyph: a carving depicting a six-legged creature with a headdress including a crown and two spheres. The shamans participated in the carving which was used in observations of the stars and in part of the Chumash calendar.