In which country was papyrus developed and production thereof kept secret?

Explanation

Papyrus is made ​​from the plant 'cyperus papyrus' and is one of the world's oldest writing materials. It was developed in Egypt around 4000 BC and manufactured under state monopoly. Hereby the method of production remained a well kept secret. The recipe was passed on orally from generation to generation of producers. The plant was considered sacred. Its flower symbolized the sun, while the triangular stem symbolized the Egyptian sign for infinity.