The invention of the dumpling might be as early as the invention of dough and boiled water. Dumplings may have been around before breads or even porridge, perhaps the first, simplest way humans figured out how to cook wild grains.
Hand ground millet may not produce the most beautiful dumplings, but these boiled lumps of dough and “filling” are meant to be a more primitive style proto-dumpling, the kind of early processes that would eventually lead to the later artistry of dumpling making in Ancient all the way to modern China.
As for fermented vegetables, while we feature them for our early Chinese dumplings recipe, Ancient China was by no means the only group of peoples to ferment vegetables. The simple process of brining food in salt water for several days to induce natural preservation and robust pickly flavor (unknown at the time to be microbial life and fermentation) was practiced all over the Ancient world, on all kinds of foods.
You can ferment any vegetable and use any spices you want. Really. Anything. Be like a true ancient and never be afraid to experiment. Here is a mix of in season veggies from my garden: carrots, green and wax beans, and rhubarb, with fresh coriander seeds and a couple cloves of garlic. All of which, though maybe in more primitive forms, would have been available in Europe and Asia long ago.