Tributaries of the Yellow River
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The Wei River (渭河), and the lower part of the Yellow River (黄河) were the cradles of Chinese civilzation. The elevation on this map also hints at the importance of geography in early Chinese history.

By the by, if you zoom in you'll see a small river valley south of the Wei. That is the Han (汉/漢) river, and the origin of the name "Han" for the Chinese ethnicity. Indirectly, it is where the words 'Hanzi' and 'Kanji' come from.