There’s a good reason KC is known as the “meltin’ pot” of barbecue sauces. They use everybody else’s to stir up their sauce. They use tomato sauce, vinegar, salt, molasses, mustard, chilies or red pepper, sugar (brown or white) and stir it into a thick (not as thick as the Texan’s however) sauce.
Most commercially bottled sauces are basically Kansas City style sauces as barbecuers nationwide have expressed their love of this thick, sweet, tangy, red style of BBQ sauce.
Kansas City also hosts the only “barbecue sauce only” contest in the US. Originally called the “Diddy-Wa-Diddy Sauce Contest” it’s now been re-named (God knows why) the National Barbecue Sauce Contest.