I want to know the answer to the following question:
The earliest colloquial stratum can be traced to what?
All the background I'm provided with is that "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.". Is that enough to answer the question?
Answer: yes