This is strong evidence of asymptomatic circulation.
This conclusion is not in contradiction to the evidence behind your previous comment. In mid-February with ~60k confirmed cases that would be 300-600k asymptomatic ones. Which means that China did not have millions of asymptomatic people at the time. And so it is no surprise that a broad testing regime failed to find what did not exist at that time.
However what it also means is that as the number of confirmed cases skyrockets, it WILL be true (and possibly already is) that the number of asymptomatic cases will be in the millions.