Below you will find an excerpt from Unesco.De
Nationwide Inventory of Intangible Cultural Heritage
The covering of roofs with reeds is one of the oldest craftsmanship techniques to do with house construction, and had been verifiably practised as early as ca. 4,000 B.C. Originally it had been roofs in rural areas which the builder of the house had constructed using his own means from the tried and tested, regionally available materials reed or straw.
It is the common reed or bulrush that today serves as a basic material for thatched roofs. Thatched roofs are widespread in many regions of Europe, Asia and Africa. In Germany they are predominantly to be found in those areas of Northern Germany close to...(Read the rest of the article on their website)