I have a fantasy world with merfolk in it who have their own underwater civilization. While they are capable of trading and obtaining material from humans I want to figure out how much technology they could create on their own, using the natural resources around them. The time period the setting is based on is around 500 B.C. on earth.
I would want to know if my merfolk could accomplish making rope or weaving textiles on their own, because I think having something to tie other things with is very vital for most civilizations.
Kelp and animal tendons would be the obvious choices, and I think baskets and mats made of woven kelp would be very practical, but the material decay too fast due to being underwater to be useful for long?