The Copper Moat Around the Prophet's Kabur

It is said that Nudadim built a copper moat around the cover of the Prophet ﷺ. The first references in the books of history are 200 and something years after this incident. And also, I asked one of the main people in charge of the sanctuary of the Prophet  's kabur and cleaning it and whatnot. And he said this is Khadib. This is a lie. There is no moat made out of copper around thecover of the Prophet ™.