There's been a couple of tidbits dropped in the little Clan Pack booklets that are implying a major rebellion in the late 4th Century. Doji Takamori, apparently known as the 'Bloody Crane', supported by Crane, Phoenix and Scorpion (and some Imperial), led a rebel army and was opposed by the Lion. The Crab meanwhile were ordered to invade the peninsula by Hantei Fujiwa, rather than just having a war with the Crane at the same time.
This seems to be the new version of the Gozoku, but is somewhat more martial.