Read this: The pronounced divergence between literary and colloquial pronunciations found in Hokkien dialects is attributed to the presence of several strata in the Min lexicon. The earliest, colloquial stratum is traced to the Han dynasty (206 BCE - 220 CE); the second colloquial one comes from the period of the Southern and Northern Dynasties (420 - 589 CE); the third stratum of pronunciations (typically literary ones) comes from the Tang Dynasty (618–907 CE) and is based on the prestige dialect of Chang'an (modern day Xi'an), its capital.
Now answer this question, if there is an answer (If it cannot be answered, return "unanswerable"): During the Tang Dynasty, in what year did the earliest stratum appear?
unanswerable