How the ancients made rice vinegar

The ancient methods I know are as follows:

1, cool cooked rice.

2, 2 bowls of rice, 2 bowls of cool white water, 3 spoons of sugar mix well into the jar.

3, sealed and kept, stored away from light put half a year.

4, half a year later take the above clarified liquid. Add a spoonful of brown sugar and seal it for another three months.

5, before bottling can be leached once again.