Annales regni Francorum
The name goes back to a place (Latin: "locus") named "Haduloha" in the Royal Frankish Annals, which must have been in the north of Hohe Lieth moraine range, west of presentday Cuxhaven. Enthusiastic historians of late 19th and early 20th century postulated an Old Saxon "Gau" (district) of that name, but there is no evidence for this theory.