The etymology of London is uncertain.[36] It is an ancient name, found in sources from the 2nd century. It is recorded c. 121 as Londinium, which points to Romano-British origin.[36] The earliest attempted explanation, now disregarded, is attributed to Geoffrey of Monmouth in Historia Regum Britanniae.[36] This had it that the name originated from a supposed King Lud, who had allegedly taken over the city and named it Kaerlud.[37]