Since approximately 10,000 BC, Syria was one of the centers of Neolithic culture (known as Pre-Pottery Neolithic A) where agriculture and cattle breeding appeared for the first time in the world. The following Neolithic period (PPNB) is represented by rectangular houses of Mureybet culture. At the time of the pre-pottery Neolithic, people used vessels made of stone, gyps and burnt lime (Vaisselle blanche). Finds of obsidian tools from Anatolia are evidences of early trade relations. Cities of Hamoukar and Emar played an important role during the late Neolithic and Bronze Age. Archaeologists have demonstrated that civilization in Syria was one of the most ancient on earth, perhaps preceded by only those of Mesopotamia.