Did Buddhists invent soy sauce as a vegetarian alternative to fish sauce?

I read once, online – can’t find the cite now – that soy sauce was invented by Buddhists to provide a vegetarian alternative to the ubiquitous fish sauce. But this page insists soy sauce in China “dates back about 2,000 years, during the Zhou dynasty.” And, except for a few missionaries, Buddhism did not really arrive in China until the 6th Century CE.

Hard to say. I see from your link that Bhuddist art made it into the country by 120 BCE – wherever the art came from, the looters/obtainers may have brought soy sauce in with them, or at least the start of the idea. The missionaries were there by 67 CE, and by the end of the 2nd century CE “a prosperous community” had formed.

Could also have been a mix of two cultures behind the soy, as well.

From what I have read, the soy was originally added to the fish sauce, then only later in history was the sauce converted to a preservation of soy alone.

Could be wrong.

Buddhism came from India. Either a round about route through Afganistan and the silk road or thru Tibet.

I’d say it’s likely that fish sauce and soy sauce were parallel developments. Fish sauce came out of the coastal areas, and soy from where there were soy beans. Communication and transportation 2,000 years ago was not ubiquitous.

Some Japanese soy sauce, “shoyu”, has fish in it, but taste and historical circumstance has led to the typical soy being made from soy and wheat only.