The Tribe of the Clam was a Sican tribe that diverged from the Tribe of the Hill in 273 AD, sailing east to look for and settle a new land. They reached the Channel Islands near California in 333.
In 270, the Hill Dynasty had lost most of its power in Asia. A large portion of the Hill tribe was very militaristic at the time, demanding the rulers go to war with the Song Dynasty to regain power. Most Hill tribesmen, however, believed that it was no use, and at this moment they shouldn't wage a war.
The Clam Tribe was that militaristic faction. In 273, over 200,000 of them sailed eastward, draining Xanux of a huge portion of its population.
The Clams as Nomads
The Clams sailed around the coast of China, Korea, and Japan between 273 and 315, looking for a place to settle. They settled a few temporary camps and towns in Korea, but they were attacked by locals there too many times.
In 315, the Clams landed in western Japan tired of being nomads, and ready to settle a kingdom. They were faced by the Japanese, which weren't necessarily a country but a collection of towns.
The Japanese were very defensive. The Clams conquered a few cities near modern-day Tokyo from 315-17, but in 318 the united fiefs in Japan ousted the Clams, killing over 50,000 Clam tribesmen. The Japanese won the war and kept their land, much like the Sicans did in their war against Carthage.
In 333, the Clams reached the Channel Islands, off the coast of modern-day California. Their furious tribe easily conquered the local people and established cities immediately.
There were too many stubbourn local leaders to unite under one, so instead the new state was called the Union of Clam Casares, which was 9 casares that were overseen by a king in a central city (which constantly shifted). The casarches and the king would vote on decisions that effected the entire country.