From Du Mu's (
杜牧) Late Tang poem
《过华清宫》 (Passing Huaqing Palace):
长安回望绣成堆,
山顶千门万户开。
一骑红尘妃子笑,
无人知是荔枝来。 - 'Looking back at Chang'an, embroidery-heaps of palaces; on the summit a thousand gates, ten thousand doors all open. A single rider in red dust, and the consort smiles - no one knew it was the lychees arriving.' A sharp jab at Emperor Xuanzong running a postal relay from Lingnan for Yang Guifei's fresh fruit.