It is believed that ketchup is a replication of a type of fish sauce that was originally created in Southeast Asia. History points to the British trying to replicate a dark sauce and turning it into what is now called ketchup.
Ketchup may have evolved from ke-tsiap, a sauce made from fermented fish, which was created by the Hokkien Chinese. It was most likely brought from Vietnam to Southeastern China. It was in the 17th and 18th centuries when it turned into a type of ketchup sauce, thanks to the British. There was a recipe printed in 1732 by Richard Bradley, indicating how to make a sauce called "ketchup in paste." This sauce was not like modern ketchup, since it often included oysters, anchovies, walnuts and mushrooms. It was typically added to sauces, meat, fish and soups.
In 1812, there was a recipe written by James Mease, a horticulturist, who called tomatoes "love apples." This is the first recipe that is similar to modern ketchup. It was made with tomato pulp, brandy and spices, but did not include sugar and vinegar like today’s ketchup. The first modern-day ketchup was produced by Henry J. Heinz in 1876. He eventually started the Heinz company and sold millions of bottles by the early 1900s.