 In Lantian, white and greenish nephrite jade is found in small quarries and as pebbles and boulders in the rivers flowing from the Kun-Lun mountain range northward into the Takla-Makan desert area.River jade collection was concentrated in the Yarkand, the White Jade (Yurungkash) and Black Jade (Karakash) Rivers.From the Kingdom of Khotan, on the southern leg of the Silk Road, yearly tribute payments consisting of the most precious white jade were made to the Chinese Imperial court and there transformed into "objets d'art" by skilled artisans as jade was considered more valuable than gold or silver, and white more valuable than green.