Of mysterious etymology is Shacha Sauce.
S: 沙茶酱; T: 沙茶醬 (shā chá jiàng). this literally means 'sand tea sauce'. It contains no tea and hopefully no sand.
To add to the confusion, 沙茶 (shā chá) also means 'satay', the Indonesian / Malaysian dish with peanut sauce. There are no peanuts in Shacha sauce, either.
Instead, it is made from fish, shrimp, aromatics, and spices. It is a feature of Chaoshan cuisine aka Teochew cuisine. As with most fish-based sauces, it adds umami and saltiness to dishes.
At least one website confuses shacha sauce and satay sauce and gives a bizarre recipe for a hybrid sauce containing both shrimp and peanuts.
Shacha sauce is used a dipping sauce and is added to stir-fries and braised dishes. A very versatile ingredient.
In the west, it is sometimes labelled 'Barbecue Sauce' and though it can be happily used as such, it's almost certainly nowhere like any BBQ sauce you're used to.
If you really do want satay, look for S: 花生酱; T: 花生醬 (huā shēng jiàng), which is peanut butter. China has many brands but also Hormel's Skippy brand is widely available. In fact, many local brands come in Skippy look-alike jars.
