Abstract: In the past 20 years,Chinese scientists have discovered a large number of Paleolithic sites in the Nihewan Basin,North China,ranging from the Lower Paleolithic to the Upper Paleolithic. Among these sites,Xujiayao,Que' ergou and Banjingzi,situatd on the top of lake deposit or the third terrace, were dated to the Middle Paleolithic;the Lower Xinmiaozhuang, Shenquansi and Xibaimaying, found in the bottom of the second terrace,were dated to the early Upper Paleolithic;while Hutouliang, Jiqitan, Erheshanggou, the Upper Xinmiaozhuang, and Youfang were dated to the late Upper Paleolithic sites, and Toumafang and Yujiagou,situated in the upper section of the second terrace,were dated to Paleolithic-Neolithic transitional period. Stone artifacts collected from these sites provide basic materials for the study of the change of raw material exploitation strategies from the Middle to the Upper Paleolithic in the Nihewan Basin.
Not all kinds of rock are suitable for stone tool manufacture, and the most frequently used materials by the Paleolithic people in the Nihewan Basin are vein quartz, chalcedony, volcano breccia, concealed crystal silicon, etc. Vein quartz is broadly distributed and can be easily obtained within the Nihewan Basin but with relatively low quality. Chalcedony and some volcanic rock are only located in limited areas,such as the Huiquanbao Village,Yangyuan Country and along some branches of the Sangganhe River. They can be easily obtained in these areas and have better quality than the vein quartz. Chalcedony materials are relatively hard with smooth and homogeneous internal consistency, but are generaly small in size,mostly smaller than 5 cm in diameter. Volcano breccia can be found in the cental areas of the basin,such as Guaijiawan and Xinmiaozhuagn. Concealed crystal silicon is distributed in the eastern areas of the basin,such as Youfang and Donggutuo. The latter two kinds of rock have very similar texture, that is,some part is fine while some is coarse.
In order to compare raw material exploitation strategies between different ages and different areas, the basin where the target archaeological sites were located was divided into three parts: the East, Central, and the West.
The East Part: Concealed crystal silicon is the principal raw material used in the eastern part of the Nihewan Basin. Though it is used as raw material by three sites—Banjingzi, Youfang and Toumafang, the exploitation degree is different from site to site. Among them, the Youfang site, the youngest in the sequence and nearest to the raw material source, yields well-made artifacts,which may be related to the application of microblade technology.
The Central Part: Sites within the central part of the basin include Que'ergou, Daxiliangnangou, Hutouliang,Yujiagou and Xinmiaozhuang. Several kinds of raw material were exploited at these sites, but volcano breccia is the most frequently used material in this region.
The West Part: Xujiayao, Shenquanis, Xibaimaying and Erheshenggou sites are situated in this district. While vein quartz and chalcedony are both used in the former three sites, the utilization of chalcedony here is unique. The exploitation of volcano breccia at the Erheshanggou site is another special character of this area.
After comparing all the sites in the basin by their distance to the material sources, the preference of different raw materials selected, and the technology in processing these materials, some interesting phenomena were observed through time:
The Middle Paleolithic: People at the three Middle Paleolithic sites, situated in different part in the basin, made use of different raw materials, i. e., lava and vein quartz as the main raw material at Que' ergou, vein quartz and chalcedony at Xujiayao, and concealed crystal silicon at Banjingzi. However, they are all local materials, obtained near the sites, within 10 km in distance.
The early Upper Paleolithic: No distinct change in the way raw material were handled can be observed at sites of this period from the previous one. However, a piece of volcano breccia and some chalcedony pieces were found at Xinmiaozhuang,which might indicate that ancient people had extended their activity range to 10 kilometers by accident.
The late Upper Paleolithic: In this period, great progress had been made in raw material selec- tion. First, vein quartz almost disappeared from the site because of its poor quality ;Chalcedony was seldom used, probably because its volume is too small to be used to produce microblade, even though its quality is fine. In the meantime, concealed crystal silicon and volcano breccia became the predominant raw material. Second, high-quality materials were transported beyound the ten-kilometer limitation. Volcano breccia,which is the characteristic material in the Central Part, appeared at the Youfang site of the East Part and the Erheshanggou site of the West Part,while the two sites are 70—80 km apart, and concealed crystal silicon was discovered in Yujiagou, 18 km west to the Youfang site in the East Part. Such material was also found at the Ma' anshan site. Third, some raw materials were flaked in their original place and only tool-blanks were brought to the site.
Based on the above observations and analyses, it is concluded that:
1. The activity territory of ancient people in the Nihewan Basin had been gradually extended from the Middle to Upper Paleolithic, from within 5 —10 km to more than 10 km, and the frequency of long- distance activity increased.
2. More and more attentions were paid to the selection of higher-quality raw material through time.
3. The use of poor-quality material, especially vein quartz, decreased through time, even though it is the most abundant material in the basin.
4. Distance of raw material source to archaeological site played an important role in the way these materials were treated and processed. Materials that could be easilty obtained were usually exploited casually,while materials that could only be procured from long distance would be selected and processed carefully. Of course there are other factors that can influence the processing of certain raw materials. For instance, people occupied the Youfang site fabricated delicate tools on concealed crystal silicon, a material with its source very close to the site, as a result of the application of microblade technology.

Key words: Raw material; Middle-Upper Paleolithic; Nihewan Basin