In the assessment of John Munro, 'the medieval scarlet was therefore a very high-priced, luxury, woollen broadcloth, invariably woven from the finest English wools, and always dyed with kermes, even if mixed with woad, and other dyestuffs.
The most obvious route for the Arabic word siklāt to have entered the Romance languages would be via the Arabic-speaking Iberian region of Al-Andalus, particularly Almería, where kermes was produced extensively.
They argued that the word spread from Germanic to other European languages due to the dominance of the Low Countries in the medieval wool trade.
It is now thought that terms like Old High German schar-lachen, Middle Low German scharlaken, and the Scandinavian derivatives (Danish skarlagen, Swedish skarlakan, Icelandic skarlak, skarlakan) originally referred to highly sheared cloth produced on the horizontal treadle loom that came into use in northern Europe around the eleventh century.
[1] It is probable that the name of the character Will Scarlett in the Robin Hood legends referred to this type of cloth, similarly to the common occupational surnames (e.g. Weaver, Cooper, Fletcher, etc.