Complex sentence: The source of the Wei River is close to Weiyuan County (渭源 literally means "Wei's source") in Gansu province, at less than 200 kilometres from the Yellow River at Lanzhou.
Split into simpler sentences: The source of the Wei River is close to Weiyuan County in Gansu province. At its source, it is less than 200 kilometres from the Yellow River at Lanzhou.