@hashcash, this is controversial because Theravada says they are the oldest surviving school. However, as more archeological discoveries are translated, it seems Mahayana like schools pre-existed the school called Theravada. Many canons have been lost forever so we may never know what the original teachings contained for each school. One point that can't be argued the sutta's in the Theravada Pali Canon, the Chinese Agamas, and Tibetan Canons are almost identical. That in itself is remarkable.