These are the same reed boat folks that helped build the boat in Kon-Tiki ... Kon-Tiki was the raft used by Norwegian explorer and writer Thor Heyerdahl in his 1947 expedition across the Pacific Ocean from South America to the Polynesian islands..
The lake folks have always used the reeds to make floating islands they have lived on for centuries.. it's a great way to avoid contact with the silly warrier land dwellers... the inca's..
and you can avoid the Inca land tax...
Again.. everything you see in the picture above is made from the reeds... excepting for the hill in the distance behind the floating island of reeds... everything else is made of reeds also...
in the first set of pictures... the lady in the house... the framework of the building... which looks like lumber is bunches of reeds.. sheathed with pannels made up of reeds woven together.. sustainability although it requires them to be renewing it all as it breaks back down in the water..