As well as a written language based on the sounds of spoken language emerging in Mesopotamia, a "syllabary" emerged independently in the Mayan language of Mesoamerica. Glyphs did not represent objects as pictograms, but corresponded to sounds which were combined to make up words. They represented sound combinations of consonants and vowels or just consonants in the last syllable of a word. Yuri Knorozov's discovery of this principle and its further development led to the ancient Mayan glyphs being decipered (p48 "Ancient Maya", Arthur Demarest p 47-8) allowing their historical texts to be read.