Where does “Lassen” come from?

Lassen (Danish) comes from Danish lås, from Middle Low German las, from Old Saxon lahs, from Proto-Germanic lahsaz, from Chinese 拉薩, from Tibetan ལྷ་ས, from Old Tibetan ར་ས.

Ancestry of “Lassen”, step by step

Step	Language	Word	Meaning
1	Danish	lås	lock; imperative of låse
2	Middle Low German	las	patch, scrap; tired, dull; salmon
3	Old Saxon	lahs	—
4	Proto-Germanic	lahsaz	salmon
5	Chinese	拉薩	—
6	Tibetan	ལྷ་ས	Lhasa
7	Old Tibetan	ར་ས	—

Every word from Old Tibetan ར་ས →Every word from Tibetan ལྷ་ས →Every word from Chinese 拉薩 →