I think my mum cast on a few stitches and knit back and forth increasing until she had 32 stitches. She made two pieces like that. Then she put 16 stitches on each of 4 needles and began knitting in the round.
Finishing: the bottom of the bag was crocheted together. At the point is a lovely detail: 3 small loops.
Here is a teacher' manual from 1929.
It was my aunt´s button bag, and there are still small pieces of sewing thread inside - and I will keep it like that.