[asveikau]

I may be off by 100-200 years, but this is what I read. There were accents and regionalisms but they were all mutually intelligible.

It is an example I think of often, about how quickly languages can change. In the scale of 1000 years, a lot changes. Most of the diversity in Romance languages is from around that timescale too, it really started to diverge substantially around 900ad-1100ad.