I'm writing a story that uses as a significant event the Hai Ba Truong, the sisters who freed Vietnam from Han Chinese rule in 41 AD. They committed suicide in the Hat River.
I need to know if the Hat River has a lake on it that could be appropriately haunted by the spirits of the dead from that time, and to do that, I need to know its name. Either the name has changed since 43 AD, or else it's REALLY small. I'm not turning it up on maps, nor am I turning it up on Google, other than in reference to the Hai Ba Truong. So it's sort of like a vicious circle there, really.
I'm not sure if it's the Red River, the Mekong, or another river entirely that is still named the Hat; any help would be vastly appreciated. I suspect it COULD be the Red or the Mekong based on the articles I have turned up, but I haven't found anything that conveniently says "The Hat River's name was changed under the reign of Emperor Whosit in 1850 to the Mekong, a word that means "look at my fancy hat, you very silly foreigners"."