The pre-Christian religion of the Anglo-Saxons, the Germanic peoples settled in Britain from the fifth century, is known only in fragments, for its adherents left no scripture and little writing. Its chief gods are glimpsed above all in the names of the weekdays: Tiw (a war-god, cognate of Norse Tyr) in Tuesday, Woden (chief god, cognate of Odin) in Wednesday, Thunor (the thunderer, cognate of Thor) in Thursday, and the goddess Frig in Friday, English renderings of the Roman planetary days. Woden looms largest: royal houses traced their genealogies back to him, using descent from the god to legitimate their rule. Because the direct English record is so sparse, much of what is written about Anglo-Saxon belief is reconstructed by comparison with the far better-attested Norse mythology of Scandinavia, a method that is useful but must be handled with care, since the two traditions were separated by centuries and by the sea.