The rich soil of the Indus Valley made productive agriculture possible. Farmers cultivated a variety of crops including wheat, rice, and barley; they also raised chickens, cattle, and buffalo. To irrigate their fields, the farmers created a series of canals and ditches. Trade was also an essential element of life in the Indus Valley. Using transportation that most likely included carts, boats, and pack animals, the people of the region traded goods with both neighboring and distant communities. These goods included grain, cotton, and farm animals. Indus Valley artisans created many fine articles, some for ornamental use and others for practical purposes. Decorative articles included ceramic beads, ornaments, and gold and silver jewelry, while useful articles included bronze and copper tools, pots, and pans as well as stone utensils. Among the most interesting types of Harappan art objects, however, are seals like the ones shown here. These seals are the only known examples of the picture writing of the Harappans. Although scholars have been unable to decipher this writing, many believe that the Harappans used the seals to stamp property or to identify its owners. Because Harappan seals have been found in the Tigris-Euphrates region near the sites of Sumerian civilization, scholars think that the people of the Indus Valley traded with people of Southwest Asia.