Complex sentence: Sometimes shepherds and farmers pick them up in the grasslands or while cultivating fields, and because some dzi are found in the earth, some Tibetans don't conceive of them as man-made.
Split into simpler sentences: Sometimes shepherds and farmers pick them up in the grasslands or while cultivating fields. Because some dzi are found in the earth, some Tibetans don't conceive of them as man-made.