The study of language began in India with Pāṇini, the 5th century BC grammarian who wrote about the 3,959 rules of Sanskrit grammar, which described the different kinds of vowels and consonants of Sanskrit as well as its verb and noun classes. In the Middle East, Sibawayh (سیبویه) wrote a book about Arabic in 760 AD, "Al-kitab fi al-nahw" (الكتاب في النحو, "The Book on Grammar") and was the first known author to talk about the difference between sounds and phonemes.