Originally it didn't have tomatoes.
We wouldn’t actually recognize the ketchup. We think of a thick gloopy red sauce made from tomatoes but to the Georgians it originally meant a dark brackish liquid infused with fermented fish extracts and, later, a type of runny chutney made from items such as fermented walnuts, or mushrooms. The tomato didn’t make an appearance in ketchup before 1800, and sugar really only became an ingredient fifty years after that....the article includes this recipe is from Eliza Smith's The Compleat Housewife, or Accomplish’d Gentlewoman’s Companion, in 1727
and he notes the origin of the word:
Etymologists argue whether the word has Chinese or Malay origins – certainly it came to Britain with various spelling variants, Jonathan Swift was describing it as’ catsup’ back in 1730. Katchup, Catchup, and Kitchup were alternative spellings to a product which quickly became phenomenally popular throughout the English speaking world.Diffen.com says it comes from Chinese:
(ketchup/catsup is) derived from the Chinese ke-tsiap, a pickled fish sauce. It made its way to Malaysia where it became kechap and ketjap in Indonesia.the Language of Food says:
They note it is no Han Chinese, but from the Min (cantonese) dialect of southern China and includes a map line to show where Patis is used vs soy sauce use. (we use both).
What was this Asian sauce? It's clear from the earliest English recipes that the original ketchup was fish sauce, the stinky cooking sauce called nuoc mam in Vietnam, nam pla in Thailand, patis in the Philippines, and made from salting and fermenting anchovies.
And the blog has a long explanation of the word's usage in SE Asia and southern China.
And did you know here, we have banana catsup here in the Philippines? It tastes almost the same as the American ketchup, which we also can buy locally....
but when I lived in Africa, I actually brought a big bottle of ketchup with me, because the British ketchup was very vinegary in taste, not sweet like Heinz...